The manganese superoxide dismutase Val16Ala polymorphism is associated with decreased risk of diabetic nephropathy in Chinese patients with type 2 diabetes

The aim of the present study was to evaluate the relationship of the manganese superoxide dismutase (MnSOD) Val16Ala (V16A) polymorphism with type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN) in Chinese patients, a case-control study was performed. This case-control study included 172 non-diabetic (non-DM) subjects and 257 T2DM patients with or without DN. Among T2DM patients, 154 had DN [albumin excretion rate (AER) >or= 30 mg/24 h] and 103 did not (AER < 30 mg/24 h), but the latter with known diabetes duration >or=10 years. The DN patients were further divided into groups with microalbuminuria (DN-1; n = 92; 300 > AER >or= 30 mg/24 h) and overt albuminuria nephropathy (DN-2; n = 62; AER >or= 300 mg/24 h). PCR-restriction fragment length polymorphism (RFLP) was used to detect genotypes of the V16A polymorphism for all subjects. The genotypic distributions of the V16A polymorphism in non-DM and T2DM subjects were in Hardy-Weinberg equilibrium and Ala allelic frequencies did not differ (11.9% vs. 9.1%; P > 0.05). The AA+VA genotypic frequencies of DN patients were significantly lower than those of non-DN patients (11.6% vs. 24.3%; P = 0.008). Multiple logistic regression analysis revealed that except for HbA1C, triglyceride, and BMI, which were high risk factors for the development of DN, the AA+VA genotype of the MnSOD-V16A polymorphism was an independent protective factor from the development of DN (odds ratio = 0.42; 95% CI = 0.18-0.95; P = 0.037) in T2DM patients. Our results suggested that the MnSOD-V16A polymorphism is associated with decreased risk of diabetic nephropathy in Chinese patients with type 2 diabetes.     

Influence of the PPAR-gamma2 Pro12Ala and ACE I/D polymorphisms on insulin sensitivity and training effects in healthy offspring of type 2 diabetic subjects.

Aerobic endurance training improves insulin sensitivity, and is of great importance in the prevention and treatment of type 2 diabetes. The improvement in insulin sensitivity and cardiovascular function through exercise is highly variable among individuals, and is probably partly determined by genetic components. This study evaluated the peroxisome proliferation-activated receptor-gamma2 ( PPAR-gamma2) Pro12Ala polymorphism and the angiotensin converting enzyme ( ACE) I/D polymorphism with respect to any potential influence that these highly prevalent polymorphisms may impose on changes in insulin sensitivity and maximal aerobic capacity induced by exercise. Seventy-nine healthy first-degree relatives of type 2 diabetic patients were compared to a control group consisting of 54 subjects without any family history of type 2 diabetes. All subjects had a normal OGTT. The groups were comparable with respect to age (34 +/- 7 vs. 33 +/- 7 years), gender ((m/f) 43/36 vs. 30/24) and BMI (25.7 +/- 2.6 vs. 25.3 +/- 2.5 kg/m (2)); p (all) = NS. Furthermore, a subgroup of 29 offspring and 17 control subjects were engaged in a standardized training program lasting ten weeks. Insulin sensitivity (hyperinsulinemic euglycemic clamp technique) and VO (2)max (exhaustive exercise test) was assessed before and after the training period. We will demonstrate the allelic frequency of the Ala-allele of the Pro12Ala polymorphism to be lower in offspring to type 2 diabetic patients (13.3 %) compared to control subjects (21.3 %); p < 0.05. In offspring only, the Pro12Ala polymorphism of the PPAR-gamma2 gene appeared to enhance weight changes brought about by exercise (Deltaweight = - 0.3 +/- 1.4 kg vs. - 1.8 +/- 1.8 kg; p < 0.05; (Pro/Pro vs. Pro/Ala + Ala/Ala) - suggesting possible gene-environment or gene-gene interactions. The ACE I/D polymorphism was not of significant importance in determining the capability of responding to exercise in terms of improvement in insulin sensitivity or maximal aerobic capacity.     

The effect of etomoxir on insulin sensitivity in type 2 diabetic patients.

Oral application of 50 mg Etomoxir caused a significant rise (33.1%) of insulin-mediated glucose uptake. This was shown in a placebo-controlled, double-blind randomized study in 8 type 2 diabetic patients by using the euglycemic clamp technique. The mean metabolic clearance rate of glucose (MCR) was raised from 4.1 +/- 0.9 mg/(kg.min) to 5.4 +/- 1.2 mg/(kg.min) (x +/- SEM, P = 0.039). Plasma levels of free fatty acids (FFA), glucose counterregulatory hormones, lipids and C-peptide values during the clamps were not different after verum and placebo. We conclude that Etomoxir improves insulin sensitivity in type 2 diabetic patients.     

Evidence for greater oxidative substrate flexibility in male carriers of the Pro 12 Ala polymorphism in PPARgamma2.

The Pro12Ala polymorphism of the peroxisome proliferator-activated receptor gamma2 (PPARgamma2) gene is associated with reduced type 2 diabetes risk and increased insulin sensitivity. It is possible that the oxidative shift from lipid to glucose as a fuel is more efficient in Ala allele carriers. To test this hypothesis, we examined carbohydrate and lipid oxidation by indirect calorimetry in lean, glucose tolerant subjects with (X/Ala, n = 25) and without the Pro12Ala polymorphism (Pro/Pro, n = 73) basally and after insulin stimulation during a 2-hour eugylcaemic hyperinsulinaemic clamp. Insulin sensitivity was non-significantly greater in X/Ala (0.13 +/- 0.01 micromol/kg/min/pM) than in Pro/Pro (0.12 +/- 0.01 micromol/kg/min/pM, p = 0.27). Basally, there were no lipid nor carbohydrate oxidation differences between the groups. Interestingly, the decrease in lipid oxidation during insulin stimulation was significantly greater in male X/Ala (- 0.51 +/- 0.06 mg/kg/min) than in male Pro/Pro (- 0.35 +/- 0.04 mg/kg/min, p = 0.03). No difference was observed in females. Analogously, the change in carbohydrate oxidation in male X/Ala (1.34 +/- 0.2 mg/kg/min) was significantly greater than in male Pro/Pro (1.03 +/- 0.12 mg/kg/min, p = 0.05). The respiratory quotient increased more, but not significantly more, in male X/Ala (0.11 +/- 0.01) than in male Pro/Pro subjects (0.08 +/- 0.01, p = 0.08) but similarly in females. These results indicate that the mechanism by which the Ala allele improves insulin sensitivity might involve enhanced suppression of lipid oxidation permitting more efficient (predominantly non-oxidative) glucose disposal. It is unclear why this could be demonstrated only in males, although gender differences in substrate oxidation are well documented.     

Alcohol intake modulates the genetic association between HDL cholesterol and the PPARgamma2 Pro12Ala polymorphism

The peroxisome proliferator-activated receptor gamma (PPARgamma) Pro12Ala polymorphism affects plasma lipids, but to what extent alcohol intake interferes with this association remains unknown. We randomly recruited 251 nuclear families (433 parents and 493 offspring) in the framework of the European Project on Genes in Hypertension study and genotyped 926 participants in whom all serum lipid variables and information on alcohol consumption were available for PPARgamma2 Pro12Ala. Genotype-phenotype relations were assessed using generalized estimating equations (GEE) and a quantitative transmission disequilibrium test (QTDT). The Ala12 allele was more frequent in Novosibirsk (0.17) than in Cracow (0.12) and Mirano (0.11) (P < 0.01). Using GEE (P = 0.03) or QTDT (P = 0.007), Italian offspring carrying the Ala12 allele had higher serum HDL cholesterol than noncarriers. HDL cholesterol levels were on average 0.086 mmol/l (P = 0.001) higher in drinkers than in nondrinkers. Compared with Pro12 homozygotes, Ala12 allele carriers consuming alcohol had higher serum total and HDL cholesterol, with the opposite trend occurring in nondrinkers. This genotype-alcohol interaction was independent of the type of alcoholic beverage and more pronounced in moderate than in heavy drinkers. We conclude that alcohol intake modulates the relation between the PPARgamma2 Pro12Ala and HDL cholesterol level and that, therefore, the Pro12Ala polymorphism, pending confirmation of our findings, might affect cardiovascular prognosis.     

Carotid artery intima-media thickness is associated with insulin-mediated glucose disposal in nondiabetic normotensive offspring of type 2 diabetic patients

The aim of this study was to investigate whether insulin resistance is independently associated with early manifestations of atherosclerosis. To this end, 176 normotensive offspring of type 2 diabetic patients were subjected to euglycemic hyperinsulinemic clamp to assess insulin sensitivity. Early atherosclerosis was studied by ultrasonography of the common carotid artery. Of the total 176 subjects, 145 were glucose tolerant, 18 had impaired fasting glucose, and 13 had impaired glucose tolerance. Univariate correlations showed that age, body mass index, waist, blood pressure, 2-h postchallenge glucose, fasting insulin, triglycerides, interleukin-6, fibrinogen, and white blood cell count were significantly correlated with carotid intima-media thickness (IMT), whereas HDL cholesterol and glucose disposal showed a negative correlation. A stepwise multivariate regression analysis including sex, age, waist circumference, smoking status, systolic blood pressure, diastolic blood pressure, triglyceride, HDL cholesterol, 2-h postchallenge glucose, plasma IL-6, fibrinogen, white blood cell count, insulin-stimulated glucose disposal, and fasting insulin showed that the four variables that remained significantly associated with carotid IMT were waist circumference, insulin-stimulated glucose disposal, white blood cell count, and diastolic blood pressure, accounting for 33.7% of its variation. These findings support the concept that insulin sensitivity, rather than plasma insulin levels, is associated with early atherosclerosis in nondiabetic normotensive offspring of type 2 diabetic patients.     

Association of soluble epoxide hydrolase gene polymorphism with insulin resistance in type 2 diabetic patients

The insulin resistance found in diabetes is influenced by vascular tone and local blood flow. Endothelial-derived hyperpolarizing factor (EDHF) functions as a potent vasodilator to regulate vascular tone, and its production is regulated by soluble epoxide hydrolase (sEH). In this study, we examined the genotype distribution and allele frequency of sEH gene G860A (Arg287Gln) polymorphism in Japanese subjects (n=499) (non-diabetic subjects, n=205; type 2 diabetic patients, n=294). Also, to accurately evaluate insulin resistance, we performed the euglycemic hyperinsulinemic clamp test for each type 2 diabetic patient (n=86) from whom agreement was obtained, and then examined a possible association of sEH gene G860A polymorphism with insulin resistance status. There was no significant difference in genotype distribution and allele frequency between non-diabetic subjects and type 2 diabetic patients. Interestingly, however, there was close association of sEH gene G860A (Arg287Gln) polymorphism with insulin resistance in type 2 diabetic patients, which was not observed in non-diabetic subjects. These results suggest that sEH and EDHF play some important role in the pathogenesis of insulin resistance found in type 2 diabetes.     

Simplified measurement of insulin sensitivity with the minimal model procedure in type 2 diabetic patients without measurement of insulinemia.

This study aimed to evaluate a simplified minimal model protocol for measuring insulin sensitivity in mild and severe type 2 diabetes, considering that changes in serum insulin during an insulin-modified intravenous glucose tolerance test almost only reflect the insulin injection. Two groups of diabetics treated with high doses of antidiabetic agents were recruited. Mean insulin responses were calculated in group 1 (n = 30). In group 2 (n = 38), we compared insulin sensitivity (SI) obtained with reference protocol with SI calculated by a minimal model procedure including the theoretical average insulin profile determined in group 1, and with Homeostasis Model Assessment (HOMA-R). Additionally, the cost of each procedure was calculated. SI measured by the reference method strongly correlated with SI determined by the simplified protocol (r = 0.966, p < 0.0001), while no correlation was found with HOMA-R (r = - 0.349, NS). Reduction of cost for HOMA-R and simplified minimal model procedure were - 92 and - 81 %, respectively. This simplified and relative inexpensive protocol, using minimal model procedure without insulin measurement, accurately measures SI regardless of beta-cell defect degree. This approach could be of interest when limits of validity of simple indexes are reached.     

PPARgamma2 Pro12Ala polymorphism in relation to free fatty acids concentration and composition in lean healthy Czech individuals with and without family history of diabetes type 2

Free fatty acids (FFAs) are natural ligands of the PPARgamma2 receptor. FFA plasma concentration and composition may represent one of the factors accounting for high heterogeneity of conclusions concerning the effect of the Pro12Ala on BMI, insulin sensitivity or diabetes type 2 (DM2) susceptibility. Our objective was to investigate the relation and possible interactions between the Pro12Ala polymorphism and FFA status, metabolic markers, and body composition in 324 lean nondiabetic subjects (M/F: 99/225; age 32+/-11 years; BMI 23.9+/-4.0 kg/m(2)) with and without family history of DM2. Family history of DM2 was associated with lower % PUFA and slightly higher % MUFA. The presence of Pro12Ala polymorphism was not associated with fasting plasma FFA concentration or composition, anthropometric or metabolic markers of glucose and lipid metabolism in tested population. However, the interaction of carriership status with FFA levels influenced the basal glucose levels, insulin sensitivity and disposition indices, triglycerides, HDL-cholesterol and leptin levels, especially in women. The metabolic effects of 12Ala carriership were influenced by FFA levels - the beneficial role of 12Ala was seen only in the presence of low concentration of plasma FFA. Surprisingly, a high PUFA/SFA ratio was associated with lower insulin sensitivity, the protective effect of 12Ala allele was apparent in subjects with family history of DM2. On the basis of our findings and published data we recommend the genotyping of diabetic patients for Pro12Ala polymorphism of the PPARgamma2 gene before treatment with thiazolidinediones and education of subjects regarding diet and physical activity, which modulate metabolic outcomes.     

Uncoupling protein 2 G(-866)A polymorphism: a new gene polymorphism associated with C-reactive protein in type 2 diabetic patients C-reactive protein in type 2 diabetic patients

Objective

To evaluate glycemic variability associated with two different premixed insulin analogue formulations when used in a twice-daily regimen.

Patients and Methods

Subjects comprised type 2 diabetic patients aged 20-79 years, treated with twice daily premixed insulin or insulin analogue formulations. All subjects were hospitalized for 6 days and randomized to receive either Humalog Mix 25 (Mix 25) or Humalog Mix 50 (Mix 50). They were then crossed over to the other arm between day 3 and day 4 of the study. Continuous glucose monitoring (CGM) was performed on all subjects to examine the differences in glycemic variability.

Results

Eleven type 2 diabetic patients were enrolled. No significant difference was found in 24-hour mean glucose values and their SDs, pre-meal glucose values, increases from pre-meal to peak glucose values, or time to peak glucose levels between either group. However, the mean glucose values observed during 0-8 hrs were significantly lower with Mix 25 compared to Mix 50 (128 vs. 147 mg/dL; p = 0.024).

Conclusions

The twice-daily Mix 25 regimen provided superior overnight glycemic control compared to the Mix 50 regimen in Japanese patients with type 2 diabetes. However, both twice-daily regimens with either Mix 25 or Mix 50 provided inadequate post-lunch glycemic control.

Trial Registration

Current Controlled Trials UMIN000001327     

Small ubiquitin-like modifier 4 M55V polymorphism is not associated with diabetic nephropathy in Iranian type 2 diabetes patients

INTRODUCTION:

We studied the impact of small ubiquitin-like modifier 4 (SUMO4) M55V polymorphism on susceptibility to diabetic nephropathy in Iranian type 2 diabetes patients.

MATERIALS AND METHODS:

The patient group consisted of 50 Iranian type 2 diabetes patients with nephropathy, and the control group consisted of 50 Iranian type 2 diabetes patients without nephropathy. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism method for the M55V.

RESULTS:

The frequency of SUMO4 AA, AG, and GG genotypes were 23%, 18%, and 9% in the patient group and 10%, 22%, and 18% in the control group. There was no significant difference in frequency of SUMO4 genotypes in patients compared to controls.

CONCLUSION:

These findings indicate that SUMO4 M55V polymorphism is not associated with diabetic nephropathy in Iranian type 2 diabetes patients.     

Ala45Thr variation in neuroD1 gene is associated with early-onset type 2 diabetes with or without diabetic pedigree in Chinese

Objective: Based on onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous type 2 diabetes mellitus (T2DM), we investigated the Ala45Thr variation in unrelated early-onset and late-onset T2DM with or without diabetic pedigree and unrelated non-diabetic control subjects in Chinese. Methods: 175 early-onset and 194 late-onset type 2 diabetic patients were further divided into two subgroups according to with or without diabetic pedigree respectively. This NeuroD1-Ala45Thr variation were screened by PCR-direct sequencing in above 369 type 2 diabetic patients and 87 unrelated non-diabetic control subjects. We then compared the distribution of the Ala45Thr variation among the groups, searching for the predictive trends. Results: Frequencies of the variant (AA + GA genotype) in early-onset T2DM are obviously elevated, especially among diabetic pedigree subjects when compared to non-diabetic controls (p= 0.003) and late-onset T2DM subjects (p = 0.014). However, no significant differences were observed between late-onset T2DM with or without diabetic pedigree and non-diabetic control subjects. Conclusions: Our results suggest that 1) the NeuroD1-Ala45Thr variation may itself have an important role in susceptibility to or be in disequilibrium with early-onset T2DM in Chinese; 2) the Ala45Thr may affect the onset pattern of T2DM, i.e., early-onset but not late-onset T2DM in Chinese; and 3) onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous T2DM in Chinese.     

Frequency of the Pro 12Ala polymorphism of PPARgamma2 gene in Ukrainian population and its possible role in development of metabolic syndrome

Frequency of the Pro 12Ala gene polymorphism PPARg2 has been studied in 39 healthy men and 42 men with metabolic syndrome (MS) of the age of 40-65 years in Ukrainian population. The frequencies were 27.9% for 12Ala allele, 32.6% for Pro12Ala, and 4.4% for Ala1Ala that is close to the results of estimation of Czech population. The frequency of 12Ala allele was significantly less--18.4% (p < 0.05) in the persons with MS that corresponds to the pre-established information concerning the patients with diabetes of the 2nd type. A tendency has been detected to the increase of the body mass index in patients with 12Ala allele in the metabolic syndrome group.     

PARP-1 Val762Ala polymorphism is associated with risk of cervical carcinoma

PARP-1 is a nuclear enzyme that plays an important role in DNA repair, recombination, proliferation and the genome stability. The PARP-1 Val762Ala polymorphism has been associated with increased risk of developing cancers of the prostate, esophagus and lung. The aim of this study was to determine whether the PARP-1 Val762Ala polymorphism is associated with the risk of cervical carcinoma. MA-PCR was used to genotype the PARP-1 Val762Ala polymorphism in 539 women with cervical carcinoma, 480 women with CIN and 800 controls. The genotyping method was confirmed by the DNA sequencing analysis. The PARP-1 Val762Ala polymorphism was not associated with the risk of CIN. However, women carrying the PARP-1 Ala762Ala genotype were significantly susceptible to cervical carcinoma (OR: 2.70, 95% CI: 1.47-3.70), and the similar results were also found in squamous cell carcinoma (OR: 2.56, 95% CI: 1.47-3.70). In HPV positive population, the PARP-1 Ala762Ala genotype was also associated with increased risk of cervical carcinoma (OR: 5.56, 95% CI: 2.08-14.3). Our results indicate that the PARP-1 Ala762Ala genotype increases the risk of cervical carcinoma.     

A polymorphism in the cyclooxygenase 2 gene in type 1 diabetic patients with nephropathy

Diabetic nephropathy (DN), the most serious complication of Type 1 diabetes (DM1), has a strong genetic component. Cyclooxygenase-2 (COX-2), an inducible enzyme by a number of stimuli, has been implicated in pathophysiology of cardiovascular and renal disease, including DN. The allele -765C, of the -765G > C polymorphism (rs20417) in the COX-2 promoter has lower promoter activity compared with the -765G allele and protective effects in cardiovascular disease. This polymorphism was not investigated in patients with DM1 and nephropathy. The study was conducted in 779 Caucasian patients with DM1 and compared to a representative sample of healthy Czech population. The patients demonstrated lower frequencies of the CC genotype (P = 0.005). From the DM1 cohort, 153 patients met the criteria for low risk of the development of DN (LRDN, duration of DM1 > 10 years, normoalbuminuria, normotension) and 139 patients had manifest DN. There were no differences in -765G > C polymorphisms between LRDN and DN patients. Moreover, the C/G allele frequencies did not also differ between the groups. In conclusion, patients with DM1 display lower freqencies of the protective CC genotype as compared to healthy subjects. However, the study did not reveal associations of -765G > C polymorphism with the risk of DN.