Lack of age-related increase in average glycemia in a non-Westernized sample of rural Yucatec Maya females

Age-related decline in glucose processing and the associated progressively higher circulating glucose levels are considered well-established biological aging phenomena. However, their occurrence in non-Westernized populations characterized by less mechanization and dietary processing has not been well-studied. This research extends evaluation of lifestyle conditions of diet and physical activity beyond those of Westernized areas and examines aging patterns in blood glucose among rural Yucatec Maya. The purpose is to investigate whether deteriorating glucose processing is intrinsic to human aging, while controlling for body composition in a non-Westernized setting. Data were gathered from 60 nondiabetic Maya women, 40-85 years of age, living in 16 rural villages around Merida, Yucatan. Information regarding personal history, diet, and physical activity was collected through interviews. Body composition was assessed through anthropometric and derived indicators of body size, fat distribution, body mass index, intra-abdominal fat, and total fat and fat-free masses. Glycemia was measured through microvenous samples analyzed for glycated hemoglobin (HbA(1c)) and fructosamine, to demonstrate average circulating glucose under customary living conditions. As indicated by glycation, average glycemia is not higher in older Maya females (age group F for HbA(1c) = 0.88, P > 0.05; age group F for fructosamine = 0.38, P > 0.05). Further, correlations between age and HbA(1c) (r = -0.13, P > 0.05) and fructosamine (r = -0.10, P > 0.05) are negative and not significant. The absence of significant, positive age associations with HbA(1c) and fructosamine persists when effects of body composition are taken into account. Thus, decline in glucose regulation does not appear to be a feature of aging in this non-Westernized sample, suggesting that age-related deterioration in glucose processing is not universal among human populations. Results suggest that relationships of age with glycemia are linked to lifestyle differences.     

Metabolic profile and cardiovascular risk patterns of an Indian tribe living in the Amazon Region of Brazil

The Parkatêjê Indians, belonging to the Jê group and inhabiting the M?e Maria Reservation in the southeast of the state of Pará in the Amazon Region of Brazil, have suffered rapid and intensive cultural changes in recent years. This survey was designed to characterize the metabolic profile and the frequency of cardiovascular risk factors in this community. Ninety subjects (90.0% of the adult population without admixture) were investigated. Anthropometric measurements were performed and the following clinical characteristics measured: glycemia, serum insulin and proinsulin (fasting and 2-hr post 75 g of glucose load), beta-cell function (%B) and insulin sensitivity (%S) estimated by HOMA, HbA1c, GAD65 antibody, serum lipids, uric acid, creatinine, leptin, and blood pressure. Information about alcohol use, smoking, and medical history was obtained through individual interviews. The prevalences were: overweight, 67.8%; obesity, 14.4%; central obesity, 72.2%; hypertension, 4.4%; dyslipidemia, 44.4%; hyperuricemia, 5.6%; GAD65 antibody positivity, 4.4%; smoking, 25.6%; chronic alcohol use, 0.0%. One case of impaired glucose tolerance (1.1%) and one case of impaired fasting glycemia (1.1%) were diagnosed during this study and one case of diabetes (1.1%) was diagnosed previously. The diabetic woman was excluded from the analyses involving HbA1c, glycemia, insulin, proinsulin, %B, and %S. All creatinine values were normal. Blood pressure did not correlate with age, anthropometric measurements, insulin, proinsulin, and natural logarithm (ln) transformed %S. After adjustment for age and sex, there were positive correlations between total cholesterol and body mass index (BMI; r = 0.24), triglycerides and BMI (r = 0.44), triglycerides and waist-to-hip ratio (WHR; r = 0.52), In leptin and BMI (r = 0.41), In leptin and WHR (r = 0.29), uric acid and systolic blood pressure (r = 0.34), uric acid and triglycerides (r = 0.22). Systolic (r = 0.04; r = 0.70) and diastolic (r = 0.14; p = 0.18) blood pressure did not correlate with BMI. Ln leptin had a weak positive correlation with 2-hr insulin (r = 0.14) adjusted for age, sex, and BMI. The multiple linear regression model containing the variables sex, BMI, and 2-hr insulin concentrations explained 77.2% of the variation of ln leptin. In conclusion, the high rates of cardiovascular risk factors found among these Indians point to there being a high-risk group to develop diabetes and cardiovascular diseases. To reduce this risk they need to receive preventive interventions.     

Relationship between upper and lower limb conduit artery vasodilator function in humans

Brachial artery flow-mediated dilation (FMD) is a strong predictor of future cardiovascular disease and is believed to represent a "barometer" of systemic endothelial health. Although a recent study [Padilla et al. Exp Biol Med (Maywood) 235: 1287-1291, 2010] in pigs confirmed a strong correlation between brachial and femoral artery endothelial function, it is unclear to what extent brachial artery FMD represents a systemic index of endothelial function in humans. We conducted a retrospective analysis of data from our laboratory to evaluate relationships between the upper (i.e., brachial artery) vs. lower limb (superficial femoral n = 75; popliteal artery n = 32) endothelium-dependent FMD and endothelium-independent glyceryl trinitrate (GTN)-mediated dilation in young, healthy individuals. We also examined the relationship between FMD assessed in both brachial arteries (n = 42). There was no correlation between brachial and superficial femoral artery FMD (r(2) = 0.008; P = 0.46) or between brachial and popliteal artery FMD (r(2) = 0.003; P = 0.78). However, a correlation was observed in FMD between both brachial arteries (r(2) = 0.34; P < 0.001). Brachial and superficial femoral artery GTN were modestly correlated (r(2) = 0.13; P = 0.007), but brachial and popliteal artery GTN responses were not (r(2) = 0.08; P = 0.11). Collectively, these data indicate that conduit artery vasodilator function in the upper limbs (of healthy humans) is not predictive of that in the lower limbs, whereas measurement of FMD in one arm appears to be predictive of FMD in the other. These data do not support the hypothesis that brachial artery FMD in healthy humans represents a systemic index of endothelial function.     

Postprandial endothelial function does not differ in women by race: an insulin resistance paradox?

Insulin resistance is associated with endothelial dysfunction. Because African-American women are more insulin-resistant than white women, it is assumed that African-American women have impaired endothelial function. However, racial differences in postprandial endothelial function have not been examined. In this study, we test the hypothesis that African-American women have impaired postprandial endothelial function compared with white women. Postprandial endothelial function following a breakfast (20% protein, 40% fat, and 40% carbohydrate) was evaluated in 36 (18 African-American women, 18 white women) age- and body mass index (BMI)-matched (age: 37 ± 11 yr; BMI: 30 ± 6 kg/m(2)) women. Endothelial function, defined by percent change in brachial artery flow-mediated dilation (FMD), was measured at 0, 2, 4, and 6 h following a meal. There were no significant differences between the groups in baseline FMD, total body fat, abdominal visceral fat, and fasting levels of glucose, insulin, total cholesterol, low-density lipoprotein cholesterol, or serum estradiol. Although African-American women were less insulin-sensitive [insulin sensitivity index (mean ± SD): 3.6 ± 1.5 vs. 5.2 ± 2.6, P = 0.02], both fasting triglyceride (TG: 56 ± 37 vs. 97 ± 49 mg/dl, P = 0.007) and incremental TG area under the curve (AUC(0-6hr): 279 ± 190 vs. 492 ± 255 mg·dl(-1)·min(-1)·10(-2), P = 0.008) were lower in African-American than white women. Breakfast was associated with a significant increase in FMD in whites and African-Americans, and there was no significant difference in postprandial FMD between the groups (P > 0.1 for group × time interactions). Despite being insulin-resistant, postprandial endothelial function in African-American women was comparable to white women. These results imply that insulin sensitivity may not be an important determinant of racial differences in endothelial function.     

Plasma nitrite concentrations reflect the degree of endothelial dysfunction in humans

A reduced nitric oxide availability is a hallmark of endothelial dysfunction occurring early in atherosclerosis. Recently, we have shown that plasma nitrite mirrors acute changes in endothelial nitric oxide synthase activity in various mammals, including humans. Here, we examined the hypothesis that plasma nitrite levels are reduced in humans with endothelial dysfunction and the decrease is correlated with increasing numbers of cardiovascular risk factors (RF). Plasma nitrite concentrations were quantified by flow-injection analysis. The coefficient of variation for repeated measurements of plasma nitrite was <8%, and heart rate and blood pressure at the time of blood sampling had no significant effect on nitrite values measured (n=10). Baseline levels of plasma nitrite followed a normal distribution in each group studied and decreased progressively with increasing numbers of cardiovascular risk factors (n=351, p<0.001): 351+/-13 (0 RF), 261+/-10 (1 RF), 253+/-11 (2 RF), 222+/-18 (3 RF), and 171+/-29 nmol/L (4 RF). Intima media thickness (IMT) and flow-mediated dilation (FMD) were determined via ultrasound. Plasma nitrite and FMD levels were lower, whereas IMT was greater in individuals with endothelial dysfunction (n=12) compared to healthy volunteers (n=12). Nitrite correlated significantly with FMD (r=0.56, p<0.001) and inversely with IMT (r= -0.49, p<0.01). Plasma nitrite levels are reliably measurable in humans, indicate endothelial dysfunction, and correlate with cardiovascular risk factors. Future studies are necessary to identify the prognostic relevance of plasma nitrite determination in patients suffering from cardiovascular disease.     

Plasma norepinephrine is an independent predictor of vascular endothelial function with aging in healthy women

We tested the hypothesis that reductions in vascular endothelial function (endothelium-dependent dilation, EDD) with age are related to increases in sympathetic activity. Among 314 healthy men and women, age was inversely related to brachial artery flow-mediated dilation (FMD) (r = -0.30, P < 0.001), a measure of EDD, and positively related to plasma norepinephrine concentrations (PNE), a marker of sympathetic activity (r = 0.49, P < 0.001). Brachial FMD was inversely related to PNE in all subjects (r = -0.25, P < 0.001) and in men (n = 187, r = -0.17, P = 0.02) and women (n = 127, r = -0.37, P < 0.001) separately. After controlling for PNE (multiple regression analysis), brachial FMD remained significantly related to age in all subjects (r = -0.20, P < 0.001) and in men (r = -0.23, P < 0.01), but not women (r = -0.16, P = 0.06). Consistent with this, brachial FMD remained significantly related to PNE when controlling for age (r = -0.24, P < 0.01) and menopause status (r = -0.24, P < 0.01) in women. Indeed, PNE was the strongest independent correlate of brachial FMD in women after controlling for conventional cardiovascular disease risk factors (r = -0.22, P = 0.01). This relation persisted in a subset of women (n = 113) after further accounting for the effects of plasma oxidized low-density lipoprotein (P < 0.05), a circulating marker of oxidative stress. Endothelium-independent dilation was not related to age in either men or women (P > 0.05). These results provide the first evidence that EDD is inversely related to sympathetic activity, as assessed by PNE, among healthy adults varying in age. In particular, our findings suggest that sympathetic nervous system activity may be a key factor involved in the modulation of vascular endothelial function with aging in women.     

Plasma obestatin is lower at fasting and not suppressed by insulin in insulin-resistant humans

Obestatin, a recently discovered 23-amino acid peptide, is involved in the regulation of appetite and body weight in antagonistic fashion to ghrelin, both deriving from a common precursor peptide. Ghrelin was shown to be associated with insulin resistance, which may also affect obestatin. We investigated the association between insulin resistance and plasma concentrations of obestatin and ghrelin in nondiabetic individuals with high (IS; n = 18, 13 females and 5 males, age 47 +/- 2 yr, BMI = 25.5 +/- 0.9 kg/m(2)) and low (IR; n = 18, 12 females and 6 males, age 45 +/- 2 yr, P = 0.49, BMI = 27.5 +/- 1.1 kg/m(2), P = 0.17) insulin-stimulated glucose disposal (M), measured by 2-h hyperinsulinemic (40 mU.min(-1).m(-2)) isoglycemic clamp tests. M(100-120 min) was higher in IS (10.7 +/- 0.7) than in IR (4.4 +/- 0.2 mg.min(-1).kg(-1), P < 10(-9)), whereas insulin-dependent suppression of free fatty acids (FFA) in plasma was reduced in IR (71 +/- 6% vs. IS: 82 +/- 5%, P < 0.02). In both groups, plasma ghrelin concentrations were comparable at fasting and similarly reduced by 24-28% during insulin infusion. IR had lower fasting plasma obestatin levels (383 +/- 26 pg/ml vs. IS: 469 +/- 23 pg/ml, P < 0.02). Clamp insulin infusion reduced plasma obestatin to approximately 81% of basal values in IS (P < 0.00002), but not in IR. Fasting plasma obestatin was correlated positively with M (r = 0.34, P = 0.04), HDL cholesterol (r = 0.45, P = 0.01), and plasma ghrelin concentrations (r = 0.80, P < 0.000001) and negatively with measures of adiposity, plasma FFA during clamp (r = -0.42, P < 0.01), and systolic blood pressure (r = -0.33, P < 0.05). In conclusion, fasting plasma concentrations of obestatin, but not of ghrelin, are reduced in insulin resistance and are positively associated with whole body insulin sensitivity in nondiabetic humans. Furthermore, plasma obestatin is reduced by insulin in insulin-sensitive but not in insulin-resistant persons.     

Long‐term Successful Weight Loss Improves Vascular Endothelial Function in Severely Obese Individuals

Obesity is associated with increased cardiovascular risk. Although short‐term weight loss improves vascular endothelial function, longer term outcomes have not been widely investigated. We examined brachial artery endothelium‐dependent vasodilation and metabolic parameters in 29 severely obese subjects who lost ≥10% body weight (age 45 ± 13 years; BMI 48 ± 9 kg/m²) at baseline and after 12 months of dietary and/or surgical intervention. We compared these parameters to 14 obese individuals (age 49 ± 11 years; BMI 39 ± 7 kg/m²) who failed to lose weight. For the entire group, mean brachial artery flow‐mediated dilation (FMD) was impaired at 6.7 ± 4.1%. Following sustained weight loss, FMD increased significantly from 6.8 ± 4.2 to 10.0 ± 4.7%, but remained blunted in patients without weight decline from 6.5 ± 4.0 to 5.7 ± 4.1%, P = 0.013 by ANOVA. Endothelium‐independent, nitroglycerin‐mediated dilation (NMD) was unaltered. BMI fell by 13 ± 7 kg/m² following successful weight intervention and was associated with reduced total and low‐density lipoprotein cholesterol, glucose, hemoglobin A_1c, and high‐sensitivity C‐reactive protein (CRP). Vascular improvement correlated most strongly with glucose levels (r = ?0.51, P = 0.002) and was independent of weight change. In this cohort of severely obese subjects, sustained weight loss at 1 year improved vascular function and metabolic parameters. The findings suggest that reversal of endothelial dysfunction and restoration of arterial homeostasis could potentially reduce cardiovascular risk. The results also demonstrate that metabolic changes in association with weight loss are stronger determinants of vascular phenotype than degree of weight reduction.     

Parathyroid hormone, but not vitamin D, is associated with the metabolic syndrome in morbidly obese women and men: a cross-sectional study

Background

Asymmetric dimethylarginine (ADMA) is a competitive inhibitor of endothelial nitric oxide synthase (eNOS) that is associated with endothelial dysfunction, and is a risk marker for cardiovascular disease, a significant problem in Type 1 diabetes. The aim of the present study was to measure circulating ADMA, and define its association with endothelial dysfunction and endothelial markers in people with Type 1 diabetes with low likelihood of macrovascular disease.

Methods

Sixty-one young people with Type 1 diabetes without macrovascular disease or nephropathy and 62 healthy volunteers underwent brachial artery flow-mediated dilatation (FMD) and assay of plasma ADMA and adhesion molecules.

Results

Age, gender, BMI, lipid profile and renal function were similar in the two groups. People with Type 1 diabetes had impaired FMD compared to healthy controls (5.0 ± 0.4 vs 8.9 ± 0.4%; p < 0.001). Plasma ADMA levels were significantly lower in the people with diabetes compared to healthy controls (0.52 ± 0.12 vs 0.66 ± 0.20 μmol/l, p < 0.001). Plasma ICAM-1, E-selectin and PAI-1 levels were significantly higher in people with diabetes compared to healthy controls (median 201 (IQR 172–226) vs 180 (156–216) μg/l, p = 0.027; 44.2 (32.6–60.9) vs. 33.1 (22.4–51.0) μg/l; p = 0.003 and 70.8 (33.3–85.5) vs 46.3 (23.9–76.8) μg/l, p = 0.035). Plasma ADMA and VCAM-1 levels were positively correlated (r = 0.37, p = 0.003) in people with diabetes. There was no correlation between the plasma ADMA and FMD.

Conclusion

ADMA levels are not associated with endothelial dysfunction in young adults with Type 1 diabetes without microalbuminuria or known macrovascular disease. This suggests that the impaired endothelial function in these individuals is not a result of eNOS inhibition by ADMA.     

Tetrahydrobiopterin increases insulin sensitivity in patients with type 2 diabetes and coronary heart disease

Tetrahydrobiopterin (BH(4)) is an essential cofactor of nitric oxide synthase that improves endothelial function in diabetics, smokers, and patients with hypercholesterolemia. Insulin resistance has been suggested as a contributing factor in the development of endothelial dysfunction via an abnormal pteridine metabolism. We hypothesized that BH(4) would restore flow-mediated vasodilation (FMD, endothelial-dependent vasodilation), which may affect insulin resistance in type 2 diabetic patients. Thirty-two subjects (12 type 2 diabetic subjects, 10 matched nondiabetic subjects, and 10 healthy unmatched subjects) underwent infusion of BH(4) or saline in a random crossover study. Insulin sensitivity index (S(I)) was measured by hyperinsulinemic isoglycemic clamp. FMD was measured using ultrasonography. BH(4) significantly increased S(I) in the type 2 diabetics [3.6 +/- 0.6 vs. 4.9 +/- 0.7 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P < 0.05], while having no effects in nondiabetics [8.9 +/- 1.1 vs. 9.0 +/- 0.9 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P = 0.92] or in healthy subjects [17.5 +/- 1.6 vs. 18 +/- 1.8 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P = 0.87]. BH(4) did not affect the relative changes in brachial artery diameter from baseline FMD (%) in type 2 diabetic subjects (2.3 +/- 0.8 vs. 1.8 +/- 1.0%, P = 0.42), nondiabetic subjects (5.3 +/- 1.1 vs. 6.6 +/- 0.9%, P = 0.32), or healthy subjects (11.9 +/- 0.6 vs. 11.0 +/- 1.0%, P = 0.48). In conclusion, BH(4) significantly increases insulin sensitivity in type 2 diabetic patients without any discernible improvement in endothelial function.     

The T-786C and C774T endothelial nitric oxide synthase gene polymorphisms independently affect the onset pattern of severe diabetic retinopathy.

Genetic factors could be implicated in the pathogenesis of severe diabetic retinopathy (DR). Recently, we reported a strong association between the eNOS4b/a endothelial nitric oxide synthase (eNOS) polymorphism and severe DR. To examine whether T-786C and C774T eNOS polymorphisms are involved in severe DR, 254 Caucasians with longstanding C-peptide-negative type 1 diabetes, 128 patients with absent/mild DR (control group), and 126 patients with preproliferative/proliferative DR (study group) were genotyped. The distribution of T-786C and C774T eNOS polymorphisms was in Hardy-Weinberg equilibrium and did not differ between the study and control groups. However, in case patients (n=126), T-786C and C774T polymorphisms influenced the onset pattern of severe DR (P=0.0169 and P=0.0257, respectively). The C-786C genotype was associated with early-onset severe DR (duration of diabetes: 15.2+/-5.9 vs. 19.4+/-6.3 years, P=0.0105), and the homozygous T774T genotype was associated with late-onset severe DR (24.3+/-7.0 vs. 18.4+/-6.2 years, P=0.0067). In the case of patients with high glycosylated hemoglobin levels (HbA1c >8%, n=88), the association between the T-786C polymorphism and early-onset severe DR was stronger (P=0.0068). Case patients carrying the C-786C genotype had higher HbA1c values (9.61+/-1.89%) than those carrying the T-786T genotype (8.93+/-1.47%, P=0.0173). Multivariate analysis showed that T-786C polymorphism was the best independent factor for onset pattern of severe DR (P<0.001). These findings, supported by previous associations between eNOS4b/a polymorphism and DR, suggest that T-786C and C774T eNOS polymorphisms affect the onset pattern of severe DR.     

Hemoglobin A1c Levels and Aortic Arterial Stiffness: The Cardiometabolic Risk in Chinese (CRC) Study

Objective

The American Diabetes Association (ADA) recently published new clinical guidelines in which hemoglobin A1c (HbA1c) was recommended as a diagnostic test for diabetes. The present study was to investigate the association between HbA1c and cardiovascular risk, and compare the associations with fasting glucose and 2-hour oral glucose tolerance test (2 h OGTT).

Research Design and Methods

The study samples are from a community-based health examination survey in central China. Carotid-to-femoral pulse wave velocity (cfPWV) and HbA1c were measured in 5,098 men and women.

Results

After adjustment for age, sex, and BMI, the levels of HbA1c were significantly associated with an increasing trend of cfPWV in a dose-dependent fashion (P for trend <0.0001). The associations remained significant after further adjustment for blood pressure, heart rate, and lipids (P = 0.004), and the difference in cfPWV between the highest and the lowest quintiles of HbA1c was 0.31 m/s. Fasting glucose and 2 h OGTT were not associated with cfPWV in the multivariate analyses. HbA1c showed additive effects with fasting glucose or 2 h OGTT on cfPWV. In addition, age and blood pressure significantly modified the associations between HbA1c and cfPWV (P for interactions <0.0001 for age; and  = 0.019 for blood pressure). The associations were stronger in subjects who were older (≥60 y; P for trend = 0.004) and had higher blood pressure (≥120 [systolic blood pressure]/80 mmHg [diastolic blood pressure]; P for trend = 0.028) than those who were younger and had lower blood pressure (P for trend >0.05).

Conclusions

HbA1c was related to high cfPWV, independent of conventional cardiovascular risk factors. Senior age and high blood pressure might amplify the adverse effects of HbA1c on cardiovascular risk.     

Association between DNA strand breakage and oxidative, inflammatory and endothelial biomarkers in type 2 diabetes

Evidence has been presented recently that type 2 diabetes patients have an increased level of DNA damage. This DNA damage could be associated with oxidative, inflammatory, and endothelial biomarkers and could represent a possible indication of injury in the endothelium and induction of inflammation in type 2 diabetes. To confirm this possible association, DNA strand breakage was evaluated by use of the comet assay and its association with oxidative, inflammatory, and endothelial biomarkers in type 2 diabetes patients. A case-control study (30 healthy controls and 32 subjects with type 2 diabetes) was performed to evaluate the association between DNA damage and NOx (nitrate/nitrite), interleukin-6 (IL-6), urinary albumin, fasting glucose, and glycated hemoglobin (HbA(1c)) levels. Type 2 diabetes patients presented higher DNA damage than control subjects, higher levels of IL-6 and urinary albumin, and lower NOx. Significant correlations between DNA damage and NOx (r=-0.303, p=0.016), IL-6 (r=0.845, p<0.001), urinary albumin (r=0.496, p<0.001), fasting glucose (r=0.449, p<0.001), and HbA(1c) (r=0.575, p<0.001) were reported. Our findings showed an increase of DNA damage in type 2 diabetes especially in those patients with poor glycemic control and associations among NOx, IL-6 and urinary albumin levels with DNA damage.     

Relationship between changes in brachial artery flow-mediated dilation and basal release of nitric oxide in subjects with Type 2 diabetes

Assessment of flow-mediated dilation (FMD) after forearm ischemia is widely used as a noninvasive bioassay of stimulated nitric oxide (NO)-mediated conduit artery vasodilator function in vivo. Whether this stimulated endothelial NO function reflects basal endothelial NO function is unknown. To test this hypothesis, retrospective analysis of randomized crossover studies was undertaken in 17 subjects with Type 2 diabetes; 9 subjects undertook an exercise training or control period, whereas the remaining 8 subjects were administered an angiotensin II receptor blocker or placebo. FMD was assessed by using wall tracking of high-resolution brachial artery ultrasound images in response to reactive hyperemia. Resistance vessel basal endothelium-dependent NO function was assessed by using intrabrachial administration of NG-monomethyl-L-arginine (L-NMMA) and plethysmographic assessment of forearm blood flow (FBF). FMD was higher after intervention compared with control/placebo (6.15+/-0.53 vs. 3.81+/-0.72%, P<0.001). There were no significant changes in the FBF responses to L-NMMA. Regression analysis between FMD and L-NMMA responses at entry to the study revealed an insignificant correlation (r=-0.10, P=0.7), and improvements in FMD with the interventions were not associated with changes in the L-NMMA responses (r=-0.04, P=0.9). We conclude that conduit artery-stimulated endothelial NO function (FMD) does not reflect basal resistance vessel endothelial NO function in subjects with Type 2 diabetes.     

Inflammation associated with obesity: relationship with blood and bone marrow endothelial cells

The purpose of this study was to assess the inflammatory nature of obesity and its effect on blood and bone marrow endothelial cell populations. Obese patients (BMI ≥30) had significantly higher concentrations of the inflammatory marker C-reactive protein (CRP) (P = 0.03) and lower concentrations of the anti-inflammatory cytokine interleukin-10 (IL-10) (P = 0.05). This cytokine profile is consistent with obesity being an inflammatory condition and is further supported by the significant correlation between total white blood cell count and BMI (r = 0.15; P = 0.035). High BMI was associated with significantly lower numbers of early endothelial cells (CD45(-)/CD34(+)) in the bone marrow (r = -0.20; P = 0.0068). There was also a significant inverse correlation between BMI and a more mature endothelial cell phenotype (CD45(-)/31(+)) in the blood (r = -0.17; P = 0.02). In addition, there was a significant correlation between BMI- and endothelial-related cells of hematopoietic origin (CD133(+)/VEGFR-2(+)) in the bone marrow (r = -0.26; P = 0.0007). Patients with higher plasma IL-10 and insulin-like growth factor (IGF) concentrations had higher numbers of endothelial phenotypes in the bone marrow suggesting a protective effect of these anti-inflammatory cytokines. In conclusion, this work confirms the inflammatory nature of obesity and is the first to report that obesity is associated with reduced endothelial cell numbers in the bone marrow of humans. These effects of obesity may be a potential mechanism for impaired tissue repair in obese patients.     

Effect of Diabetes Mellitus Type 2 on Salivary Glucose – A Systematic Review and Meta-Analysis of Observational Studies

Background

Early screening of type 2 diabetes mellitus (DM) is essential for improved prognosis and effective delay of clinical complications. However, testing for high glycemia often requires invasive and painful blood testing, limiting its large-scale applicability. We have combined new, unpublished data with published data comparing salivary glucose levels in type 2 DM patients and controls and/or looked at the correlation between salivary glucose and glycemia/HbA1c to systematically review the effectiveness of salivary glucose to estimate glycemia and HbA1c. We further discuss salivary glucose as a biomarker for large-scale screening of diabetes or developing type 2 DM.

Methods and Findings

We conducted a meta-analysis of peer-reviewed published articles that reported data regarding mean salivary glucose levels and/or correlation between salivary glucose levels and glycemia or HbA1c for type 2 DM and non-diabetic individuals and combined them with our own unpublished results. Our global meta-analysis of standardized mean differences on salivary glucose levels shows an overall large positive effect of type 2 DM over salivary glucose (Hedge''s g = 1.37). The global correlation coefficient (r) between salivary glucose and glycemia was large (r = 0.49), with subgroups ranging from medium (r = 0.30 in non-diabetics) to very large (r = 0.67 in diabetics). Meta-analysis of the global correlation between salivary glucose and HbA1c showed an overall association of medium strength (r = 0.37).

Conclusions

Our systematic review reports an overall meaningful salivary glucose concentration increase in type 2 DM and a significant overall relationship between salivary glucose concentration and associated glycemia/HbA1c values, with the strength of the correlation increasing for higher glycemia/HbA1c values. These results support the potential of salivary glucose levels as a biomarker for type 2 DM, providing a less painful/invasive method for screening type 2 DM, as well as for monitoring blood glucose levels in large cohorts of DM patients.     

High normal HbA(1c) levels were associated with impaired insulin secretion without escalating insulin resistance in Japanese individuals: the Toranomon Hospital Health Management Center Study 8 (TOPICS 8)

Diabet. Med. 29, 1285-1290 (2012) ABSTRACT: Aims We aimed to characterize the association of insulin resistance, impaired insulin secretion and β-cell dysfunction in relation to HbA(1c) levels in a non-diabetic range in Japanese individuals without clinically diagnosed diabetes. Methods This cross-sectional study included 1444 individuals without a history of outpatient treatment of diabetes or use of insulin or oral hypoglycaemic agents. The homeostasis model assessment of insulin resistance and beta-cell function, insulinogenic index, Matsuda index and disposition index were calculated using data from 75-g oral glucose tolerance tests and compared across quintile (Q) categories of HbA(1c) levels. Results Fasting plasma glucose and 30-min and 60-min plasma glucose (PG) levels were significantly higher when HbA(1c) exceeded 36?mmol/mol (5.4%). A HbA(1c) concentration of 36-37?mmol/mol (5.4-5.5%) (Q3) was significantly associated with a 15% lower homeostasis model assessment of β-cell function value and 31% lower insulinogenic index value compared with HbA(1c) ≤?32?mmol/mol (≤?5.1%) (Q1) (P?<0.01). Further, a HbA(1c) concentration of 38-40?mmol/mol (5.6-5.8%) (Q4) was associated with 17% (P?<0.01) and 24% (P?<0.05) reductions in those indexes, respectively. However, the homeostasis model assessment of insulin resistance was not significantly elevated and the Matsuda index was not significantly lower unless HbA(1c) exceeded 41?mmol/mol (5.9%). Individuals with HbA(1c) ≥?41?mmol/mol (≥?5.9%) (Q5) had a 69% lower disposition index than those with a HbA(1c) concentration of ≤?32?mmol/mol (≤?5.1%) (Q1). Conclusions Elevated HbA(1c) levels ≥?41?mmol/mol (≥?5.9%) were associated with substantial reductions in insulin secretion, insulin sensitivity and β-cell dysfunction in Japanese individuals not treated for diabetes. High normal HbA(1c) levels of 36-40?mmol/mol (5.4-5.8%) were also associated with impaired insulin secretion without marked insulin resistance in Japanese individuals.     

Association between hemoglobin A1c and carotid atherosclerosis in rural community-dwelling elderly Japanese men

Background

Recent studies have reported an association between both higher and lower levels of hemoglobin A1c (HbA1c) and higher mortality of diabetes patients. Like diabetes, carotid atherosclerosis is a well known lifestyle-related disease. However, no studies have yet reported an association between HbA1c levels and carotid atherosclerosis.

Methods

We conducted a cross-sectional study of 1,150 Japanese elderly men aged ≥60 years who were undergoing general health checkups. Carotid atherosclerosis was defined as a carotid intima-media thickness (CIMT) ≥1.1 mm. Since body mass index (BMI) is regarded as a cardiovascular risk factor that exerts a strong influence on both HbA1c levels and carotid atherosclerosis, we performed a stratified analysis of this risk based on BMI.

Results

Using the intermediate HbA1c quintile as a reference group, the groups in the lowest HbA1c quintiles showed a significantly higher risk of carotid atherosclerosis in patients with low BMI (≤23 kg/m²) vs. no increased risk in those with high BMI (>23 kg/m²). The association of HbA1c with carotid atherosclerosis became slightly stronger when these analyses were limited to subjects who were not taking glucose-lowering medications or medications for hyperlipidemia and cardiovascular disease. After adjusting for classical cardiovascular risk factors, adjusted odds ratios (ORs) for carotid atherosclerosis were 1.36 (0.84 to 2.20) for total subjects, 2.29 (1.12 to 4.66) for low-BMI groups, and 0.68 (0.33 to 1.41) for high-BMI groups.

Conclusions

Lower HbA1c level is a significant risk factor for carotid atherosclerosis in rural community-dwelling elderly Japanese men with low, but not high BMI, particularly in those not taking glucose-lowering medication.     

Serum 25-hydroxyvitamin D levels are associated with carotid atherosclerosis in normotensive and euglycemic Chinese postmenopausal women: the Shanghai Changfeng study

Background

Obesity is associated with the onset of type 2 diabetes mellitus (T2D), but reports conflict regarding the association between obesity and macrovascular complications. In this study, we investigated associations between cardiovascular risk factors and body mass index (BMI) and glycemic control in non–insulin-treated patients with T2D.

Methods

Authors gathered cross-sectional data from five observational studies performed in Spain. Generalized logit models were used to analyze the relationship between cardiovascular risk factors (independent variables) and 5 BMI strata (<25 kg/m², 25 to <30 kg/m², 30 to <35 kg/m², 35 to <40 kg/m², ≥40 kg/m²) and 5 glycated hemoglobin (HbA1c) strata (≤6.5%, >6.5–7%, >7–8%, >8–9%, >9%) (dependent outcomes).

Results

In total, data from 6442 patients were analyzed. Patients generally had mean values of investigated cardiovascular risk factors outside recommended thresholds. Younger patients had higher BMI, triglyceride levels and HbA1c than their older counterparts. Diastolic blood pressure, systolic blood pressure and triglyceride levels were directly correlated with BMI strata, whereas an inverse correlation was observed between BMI strata and high-density lipoprotein cholesterol (HDL-C) levels, patient age, and duration of T2D. Increased duration of T2D and total cholesterol levels, and decreased HDL-C levels were associated with a higher HbA1c category. BMI and HbA1c levels were not associated with each other.

Conclusions

As insulin-naïve patients with T2D became more obese, cardiovascular risk factors became more pronounced. Higher BMI was associated with younger age and shorter duration of T2D, consistent with the notion that obesity at an early age may be key to the current T2D epidemic. Glycemic control was independent of BMI but associated with abnormal lipid levels. Further efforts should be done to improve modifiable cardiovascular risk factors.

     

甲氨蝶呤联合羟基氯喹对类风湿关节炎合并糖尿病患者糖化血红蛋白水平的影响

目的:观察类风湿关节炎(rheumatoid arthritis,RA)合并糖尿病(diabetes mellitus,DM)患者使用甲氨蝶呤(methotrexate,MTX)联合羟基氯喹(hydroxychloroquine,HCQ)治疗前后糖化血红蛋白(glycosylated hemoglobin,HbA1C)水平的变化。方法:通过回顾性分析,选取联合使用MTX+HCQ或单独使用MTX治疗的RA合并DM患者,且在治疗前及开始治疗12个月内分别至少有1次HbA1C值,记录其年龄、性别、诊断、体重指数、使用糖皮质激素情况。计算用药前到用药后12个月内HbA1C最低值的变化。结果:40例使用HCQ+MTX和45例使用MTX患者符合入选标准。两组间年龄、性别、体重指数、用药前HbA1C水平相似,MTX+HCQ组糖皮质激素使用比例(40.00%)比HCQ组更多(26.67%)(P=0.25)。MTX+HCQ组治疗后HbA1C有明显下降(0.42%,P=0.00),且MTX+HCQ组HbA1C降低幅度高于MTX组(0.42%,0.12%,P=0.02)。结论:与单独使用MTX相比,RA合并DM患者联合使用HCQ+MTX可明显降低HbA1C水平。