Contribution of postexercise increment in glucose storage to variations in glucose-induced thermogenesis in endurance athletes

The present study was undertaken to evaluate the contribution of an increment in glucose storage to the reduced glucose-induced thermogenesis (GIT) characterizing endurance-trained individuals. For that purpose, glucose storage and GIT were determined during an oral glucose tolerance test (OGTT) in eight elite endurance athletes exercising between 6 and 16 h/week. Their values were compared with those obtained in five nontrained subjects submitted to two OGTT, i.e., before and 16 h after they had performed a 90-min vigorous exercise. As expected, endurance athletes exhibited a reduced GIT and a greater glucose storage during the OGTT in comparison to the preexercise values of nontrained subjects. Once the latter subjects had performed the 90-min exercise, their glucose storage during the OGTT was similar to the level found in athletes. This adaptation was accompanied by a significant reduction in GIT, which corresponded to 47% of the difference observed between trained and nontrained subjects when both groups maintained their usual life habits. Unlike GIT, resting metabolic rate (RMR) was found to be higher in athletes than in nontrained individuals. When subdividing the athletes into two subgroups on the basis of the duration of their weekly training, it was found that RMR was mainly elevated in those performing the higher amount of exercise. These results demonstrate that the reduced GIT characterizing endurance-trained individuals is partly explained by an increase in glucose storage during an OGTT. As further discussed, this reduced GIT is likely an indirect consequence of modifications of other energy-requiring energy processes rather than a direct result of the postexercise increment in glucose storage.     

Effect of a two-month detraining on glucose tolerance and insulin sensitivity in athletes--link to adrenal steroid hormones

Reduction in physical activity has been demonstrated to associate with the increased risk in insulin resistance and type 2 diabetes. To determine whether alteration in insulinemia, due to abstention from regular exercise training, is associated with changes in serum dehydroepiandrosterone sulfate (DHEA-S) and cortisol, 18 highly trained badminton players (21.2 +/- 0.3 years) were enrolled into a 2-month detraining study. Fasting serum insulin, glucose, DHEA-S, and cortisol were determined at trained state and at day 60 of detraining. Glucose tolerance and insulin sensitivity were assessed by an oral glucose tolerance test (OGTT). The 2-month detraining increased fasting glucose and insulin concentrations and body weight slightly, but did not significantly affect glucose tolerance and insulin response curve, in which 10 subjects had increased and 8 subjects had slightly decreased in the area under curve for insulin (IAUC). In the subjects with increased IAUC, serum cortisol was also elevated (from 0.44 +/- 0.07 to 0.83 +/- 0.26 U/l, P < 0.05) in parallel, and serum creatine kinase (CK) was unaltered during detraining. Whereas in the subjects with decreased IAUC, serum cortisol (from 0.51 +/- 0.19 to 0.54 +/- 0.14 U/l, no significance) was not changed and serum creatine kinase (from 461 +/- 179 to 151 +/- 21 U/l) was decreased during detraining. Two groups of detrained subjects exhibited a similar reduction in serum DHEA-S levels and slight elevation in body weight. The novel finding of the study is that the changes in serum cortisol, but not DHEA-S, were associated with the change in insulin sensitivity during early phase of lifestyle change from physically active to sedentary, and this response appears to be varied individually among athletes.     

Effect of prolonged intermittent hypoxia and exercise training on glucose tolerance and muscle GLUT4 protein expression in rats

We compared the chronic effect of intermittent hypoxia and endurance training on the glucose tolerance and GLUT4 protein expression in rat skeletal muscle. Thirty-two Sprague-Dawley rats were matched for weight and assigned to one of the following four groups: control, endurance training, hypoxia, or hypoxia followed by endurance training. Hypoxic treatment consisted of breathing 14% O₂ for 12 h/day under normobaric conditions, and the training protocol consisted of making animals swim 2 times for 3 h/day. At the end of the 3rd week, an oral glucose tolerance test (OGTT) was performed 16 h after treatments. At the end of the 4th week, GLUT4 protein, mRNA, and glycogen storage in skeletal muscle were determined. Endurance training significantly improved OGTT results. Glycogen content and GLUT4 protein expression in the plantaris and red gastrocnemius, but not in the soleus or white gastrocnemius muscles, were also elevated. Chronic intermittent hypoxia also improved OGTT results, but did not alter GLUT4 protein expression. Additionally, hypoxia followed by exercise training produced significant increases in GLUT4 protein and mRNA in a greater number of muscles compared to endurance training alone. Both exercise training and hypoxia significantly reduced body mass, and an additive effect of both treatments was found. In conclusion, chronic intermittent hypoxia improved glucose tolerance in the absence of increased GLUT4 protein expression. This treatment facilitated the exercise training effect on muscle GLUT4 expression and glycogen storage. These new findings open the possibility of utilizing intermittent hypoxia, with or without exercise training, for the prevention and clinical treatment of type 2 diabetes or insulin resistance.     

Plasma insulin and C-peptide responses to oral glucose load after physical exercise in men with normal and impaired glucose tolerance

Blood glucose, plasma insulin and C-peptide responses to oral glucose tolerance test (OGTT) were studied under basal conditions and immediately after 90-min exercise (60% VO2 max) in nondiabetic subjects with normal or impaired glucose tolerance. During the postexercise recovery blood glucose response to OGTT was increased in normal subjects and markedly decreased in those with impaired glucose tolerance, while insulin and C-peptide responses were diminished in both subgroups. The ratio of blood glucose to insulin was similarly elevated in all subjects. Comparing with basal conditions no significant changes were found in C-peptide to insulin ratio in response to OGTT after exercise, although a tendency towards an elevation of this ratio was noted in the subjects with impaired glucose tolerance. The data indicate that the reduced insulin response to OGTT during postexercise recovery in healthy subjects is due to diminished insulin secretion without any substantial changes in the hormone removal from blood, whereas in the glucose intolerant men the latter process may be enhanced.     

The influence of high carbohydrate diet on plasma glucose and insulin of trained subjects

In previous studies we have shown that when endurance athletes refrain from daily exercise for three days, they rapidly loose their enhanced insulin sensitivity. This finding suggests that a precompetitive high carbohydrate diet with reduced training might alter plasma glucose and insulin regulation. To test this hypothesis, six long distance runners were recruited to participate in a five-day experiment. During the first two days, the subjects fasted while running 16 km d-1. Thereafter, they consumed 16.3 MJ (3900 kcal) and 539 g carbohydrate per day for three days while remaining inactive. Before and after each portion of this experiment, an intravenous glucose tolerance test (IVGTT) was performed in fasting state. As expected, fasting with exercise induced a considerable deterioration of glucose tolerance, as reflected by lower K value and higher total area glucose during IVGTT. The high carbohydrate refeeding restored glucose tolerance to a level comparable to that observed when subjects maintain their usual life habits. However, while a decrease in insulin sensitivity is observed in subjects inactive for three days, the insulin sparing effect of exercise training is retained if this period of inactivity is preceded by two days of fast accompanied by exercise. These results show that glucose disposal and insulin response to glucose injection are not adversely modified by the precompetitive "glycogen loading" procedure.     

Effect of 10 days of physical inactivity on glucose tolerance in master athletes

Master athletes who exercise regularly appear to avoid the development of insulin resistance and deterioration of glucose tolerance (GT) commonly seen with aging. To evaluate the possibility that exercise prevents rather than masks the aging-related changes responsible for development of insulin resistance, we investigated the effects of 10 days of physical inactivity in 14 master athletes aged 61 +/- 2 (SE) yr. The response of 10 of these men to inactivity was similar to that of young athletes, with an unchanged plasma glucose response and a significantly greater insulin response to an oral glucose tolerance test (OGTT) after 10 days of inactivity. These 10 athletes appeared to have been protected against the aging-related changes in GT because their plasma glucose and insulin levels during the OGTT after 10 days of inactivity were not significantly different from those of young lean sedentary men. In contrast, a deterioration in GT occurred in four of the master athletes during 10 days of inactivity; this was sufficiently marked in two of them to be classified as impaired GT. We conclude that regular exercise may 1) protect against the development of insulin resistance and decline in GT with aging in individuals with normal GT and 2) normalize GT by means of short-term effects of exercise in some individuals with abnormal GT.     

Seven days of aerobic exercise training improves conduit artery blood flow following glucose ingestion in patients with type 2 diabetes

The vasodilatory effects of insulin account for up to 40% of insulin-mediated glucose disposal; however, insulin-stimulated vasodilation is impaired in individuals with type 2 diabetes, limiting perfusion and delivery of glucose and insulin to target tissues. To determine whether exercise training improves conduit artery blood flow following glucose ingestion, a stimulus for increasing circulating insulin, we assessed femoral blood flow (FBF; Doppler ultrasound) during an oral glucose tolerance test (OGTT; 75 g glucose) in 11 overweight or obese (body mass index, 34 ± 1 kg/m2), sedentary (peak oxygen consumption, 23 ± 1 ml·kg?1·min?1) individuals (53 ± 2 yr) with non-insulin-dependent type 2 diabetes (HbA1c, 6.63 ± 0.18%) before and after 7 days of supervised treadmill and cycling exercise (60 min/day, 60-75% heart rate reserve). Fasting glucose, insulin, and FBF were not significantly different after 7 days of exercise, nor were glucose or insulin responses to the OGTT. However, estimates of whole body insulin sensitivity (Matsuda insulin sensitivity index) increased (P < 0.05). Before exercise training, FBF did not change significantly during the OGTT (1 ± 7, -7 ± 5, 0 ± 6, and 0 ± 5% of fasting FBF at 75, 90, 105, and 120 min, respectively). In contrast, after exercise training, FBF increased by 33 ± 9, 39 ± 14, 34 ± 7, and 48 ± 18% above fasting levels at 75, 90, 105, and 120 min, respectively (P < 0.05 vs. corresponding preexercise time points). Additionally, postprandial glucose responses to a standardized breakfast meal consumed under "free-living" conditions decreased during the final 3 days of exercise (P < 0.05). In conclusion, 7 days of aerobic exercise training improves conduit artery blood flow during an OGTT in individuals with type 2 diabetes.     

Estimation of beta-cell function from the data of the oral glucose tolerance test

Although a hyperbolic relationship between insulin secretion and insulin sensitivity has been shown, the relationship has been often questioned. We examined the relationship using oral glucose tolerance test (OGTT)-derived indexes. A total of 374 Japanese subjects who had never been given a diagnosis of diabetes underwent a 75-g OGTT. In subjects with normal glucose tolerance (NGT), the ln [insulinogenic index (IGI)] was described by a linear function of ln (x) (x, insulin sensitivity index) in regression analysis when the reciprocal of the insulin resistance index in homeostasis model assessment, Matsuda's index, and oral glucose insulin sensitivity index were used as x. Because the 95% confidence interval of the slope of the regression line did not necessarily include -1, the relationships between IGI and x were not always hyperbolic, but power functions IGI x x(alpha) = a constant. We thought that IGI x x(alpha) was an appropriate beta-cell function estimate adjusted by insulin sensitivity and referred to it as beta-cell function index (BI). When Matsuda's index was employed as x, the BI values were decreased in subjects without NGT. Log BI had a better correlation with fasting plasma glucose (PG; FPG) and 2-h PG in non-NGT subjects than in NGT subjects. In subjects with any glucose tolerance, log BI was linearly correlated with 1-h PG and glucose spike (the difference between maximum PG and FPG). In conclusion, the relationship between insulin secretion and insulin sensitivity was not always hyperbolic. The BI is a useful tool in the estimation of beta-cell function with a mathematical basis.     

Effects of creatine supplementation on glucose tolerance and insulin sensitivity in sedentary healthy males undergoing aerobic training

Recent findings have indicated that creatine supplementation may affect glucose metabolism. This study aimed to examine the effects of creatine supplementation, combined with aerobic training, on glucose tolerance in sedentary healthy male. Subjects (n = 22) were randomly divided in two groups and were allocated to receive treatment with either creatine (CT) ( approximately 10 g . day over three months) or placebo (PT) (dextrose). Administration of treatments was double blind. Both groups underwent moderate aerobic training. An oral glucose tolerance test (OGTT) was performed and both fasting plasma insulin and the homeostasis model assessment (HOMA) index were assessed at the start, and after four, eight and twelve weeks. CT demonstrated significant decrease in OGTT area under the curve compared to PT (P = 0.034). There were no differences between groups or over time in fasting insulin or HOMA. The results suggest that creatine supplementation, combined with aerobic training, can improve glucose tolerance but does not affect insulin sensitivity, and may warrant further investigation with diabetic subjects.     

Positive correlation of galanin with glucose in healthy volunteers during an oral glucose tolerance test.

Galanin has been found in increased amounts in subjects with type 2 diabetes. The purpose of the present study was to determine the levels of galanin in healthy volunteers during an oral glucose tolerance test (OGTT). We enrolled 11 healthy volunteers, 4 males aged 48+/-3.56 years with BMI 27+/-0.5 kg/m (2) and 7 females aged 41.3+/-3.05 years with BMI 27.6+/-0.9 kg/m (2). All were in good health without cardiac, hepatic, renal or other chronic disease. None were taking any medication affecting glucose tolerance (beta-blockers, thiazide diuretics, and corticoids) and none had a first degree relative with type 2 diabetes. Glucose tolerance was determined by using the International Expert Committee criteria. Blood samples were collected at 0, 30, 60, 90, 120 and 180 minutes for the measurement of plasma glucose, insulin, C-peptide and human galanin (hGal). During the OGTT, hGal exhibited a significant increase from time 0 to 90 minutes (p < 0.001) and returned to the basal values at 180 minutes, while a positive correlation of blood glucose with hGal was observed during the time scale of OGTT. A significant increase was detected both in insulin and C-peptide from the early beginning of the test at 30 minutes, which remained steady until 90 minutes, and returned gradually to the basal values at 180 minutes. No relationship was found either between hGal and serum insulin, or between hGal and serum C-peptide among the healthy subjects, during the OGTT.     

Resistance and aerobic exercise: the influence of mode on the relationship between IL-6 and glucose tolerance in young men who are obese

Regular exercise lowers indicators of disease risk including some inflammatory cytokines; however, the relationship between different modes of acute exercise, cytokine levels, and subsequent glucose tolerance is unclear. The purpose was to determine the effects of resistance (RES) and aerobic (AER) exercises on interleukin-6 (IL-6) and its association with glucose tolerance 24 hours after exercise. After testing for 1 repetition maximum (1RM) and VO2peak, 10 obese (body mass index > 30 kg · m(-2)), untrained men aged 18-26 years completed 3 protocols: 60 minutes of RES, AER, and a resting (CON) condition. The RES was 2 sets of 8 repetitions and a third set to fatigue at 80% 1RM of 8 lifts using all major muscle groups. The AER was 60 minutes of cycling at 70% of VO2peak. On day 1, subjects completed the 60-minute exercise or resting protocol, and on day 2, they completed an oral glucose tolerance test (OGTT). Blood was collected before and after exercise, at 2 and 7 hour postexercise, and before and every 30 minutes during the OGTT and was analyzed for IL-6, glucose and insulin. Postexercise IL-6 was greater in RES (8.01 ± 2.08 pg · mL(-1)) vs. in AER (4.26 ± 0.27 pg · mL(-1)), and both were greater than in CON (1.61 ± 0.18 pg · mL(-1)). During the OGTT, there were no differences in glucose or insulin between conditions for single time points or as area under the curve. The RES caused greater IL-6 levels immediately after exercise that may be related to the greater active muscle mass compared to AER. Neither exercise produced enhanced glucose removal compared to control; thus, despite the greater elevation in IL-6 in RES, for these exercise conditions and this population, this cytokine did not influence glucose tolerance.     

Insulin and glucose responses during bed rest with isotonic and isometric exercise

The effects of daily intensive isotonic (68% maximum oxygen uptake (VO2 max)) and isometric (21% maximum extension force) leg exercise on plasma insulin and glucose responses to an oral glucose tolerance test (OGTT) during 14-day bed-rest (BR) periods were investigated in seven young healthy men. The OGTT was given during ambulatory control and on day 10 of the no-exercise, isotonic, and isometric exercise BR periods during the 15-wk study. The subjects were placed on a controlled diet (mean +/- SD = 344 +/- 34 g CHO/day and 3,073 +/- 155 (SD) kcal/day) starting 10 days before each BR period. During BR, basal plasma glucose concentration remained unchanged with no exercise, but increased (P less than 0.05) to 87-89 mg/100 ml with both exercise regimens on day 2, and then fell slightly below control levels on day 13. The fall of glucose content (-11 to -15%) during BR was independent of the exercise regimen and was an adjustment for the loss of plasma vol. The intensity of the response of insulin and glucose to the OGTT (integrated area under the curves) was inversely proportional to the total daily energy expenditure during BR; i.e., the largest response with no exercise, then isometric, isotonic, and ambulatory exercise. It was estimated that at least 1,020 kcal/day must be provided by supplemental exercise to restore the hyperinsulinemia to control levels.     

Assessing Impaired Glucose Tolerance and Insulin Resistance in Polycystic Ovarian Syndrome with A Muffin Test: An Alternative to the Glucose Tolerance Test

ObjectiveTo determine the sensitivity of a high-glucose load in a meal as an alternative to the standard oral glucose tolerance test (OGTT) in detecting impaired glucose tolerance and insulin resistance in women with polycystic ovarian syndrome (PCOS) and the relationship of body composition to insulin resistance in the PCOS cohort.MethodsIn this prospective, single-center study, women with PCOS who were being followed up as outpatients were recruited. The study was performed between November 2007 and March 2008. All participants underwent OGTT before study enrollment. Participants were given a meal including carbohydrates, fat, and protein. Glucose and insulin levels were measured every 30 minutes for 2 hours after completing the meal. Body composition was measured by dual-energy x-ray absorptiometry.ResultsThirteen of the 15 participants completed the meal tolerance test and the body composition study. Four of 13 participants (31%) had abnormal glucose tolerance with the meal test compared with 2 of 8 participants (25%) who completed the OGTT. Those who had insulin resistance on OGTT were detected with the meal test. The 2-hour insulin levels following the meal were 38% higher than with the OGTT. Of 10 participants with insulin resistance, 9 had a total body fat mass greater than the 90th percentile, whereas 1 of 3 participants (33%) with normal body composition was insulin resistant.ConclusionAdministration of oral glucose load via a meal is an effective alternative to the OGTT in diagnosing impaired glucose tolerance and insulin resistance and may be more sensitive, without the adverse effects of the oral glucose load in the OGTT. PCOS is an independent risk factor for impaired glucose tolerance and insulin resistance, regardless of body composition. (Endocr Pract. 2010;16:810-817)     

Incidence of exercise induced hypoxemia in elite endurance athletes at sea level

Recent evidence suggests that exercise-induced hypoxemia (EIH) may occur in healthy trained endurance athletes. However, at present, no data exist to describe the regularity of EIH in athletes or non-athletes. Therefore, the purpose of the present investigation was to determine the incidence of EIH during exercise in healthy subjects varying in physical fitness. Subjects (N = 68) performed an incremental cycle ergometer test to volitional fatigue with percent arterial oxyhemoglobin saturation (%SaO2) measured min-by-min. For the purpose of data analysis subjects were divided into three groups according to their level of physical training: 1) untrained (N = 16), 2) moderately trained (N = 27), and 3) elite highly trained endurance athletes (N = 25). EIH was defined as a %SaO2 of less than or equal to 91% during exercise. EIH did not occur in any of the untrained subjects or the moderately trained subjects. However, EIH occurred in 52% of the highly trained endurance athletes tested and was highly reproducible (r = 0.95; P less than 0.05). These findings further confirm the existence of EIH in healthy highly trained endurance athletes and suggests a rather high incidence of EIH in this healthy population. Hence, it is important that the clinician or physiologist performing exercise testing in elite endurance athletes recognize that EIH can and does occur in the elite endurance athlete in the absence of lung disease.     

Beta-cell dysfunctions and insulin resistance in subjects with increased risk for type 2 diabetes mellitus

The aim of this study was to test if a beta-cell defect is associated to deterioration of glucose tolerance early during the natural history of the type 2 diabetes mellitus . In 41 overweight women, with macrosomic infants in their antecedent deliveries, measures of insulin response and insulin sensitivity were derived from a short (45 min) iv glucose test. The early (EIR) and the late (LIR) phase insulin responses and the insulin sensitivity index (Si) were calculated. According the response to 75 g oral glucose test the subjects were divided into two groups: Imparired glucose tolerance (IGT;n = 12), and normal glucose tolerance (NGT; n = 29). EIR was reduced in IGT group (14.9 ± 3.6 vs 37.0 ± 4.0; p< 0.002). Glucose tolerance during oral glucose tolerance test (OGTT), correlated inversly to EIR (r=-0.45; n=41; p< 0.01). A strong correlation of EIR to LIR (r=0.88; n = 41; p< 0.001) but no correlation between glucose tolerance and Si was found.     

Endogenous opiate modulators of insulin secretion in the obese

The effects of endogenous opiates on insulin response to oral glucose load were studied in obese subjects and in lean healthy volunteers. None of these having a family diabetes. After 3 days on an 1,800 cal./m2, 40% carbohydrate diet all subjects underwent two standard 75 g oral glucose tolerance tests (OGTT), one of which was accompanied by an i. v. administration of 10 mg of, an antagonist of opiates, the naloxone. In one group of obese impaired oral glucose tolerance test occurred. All obese, but not the lean healthy volunteers, showed: 1) increased basal plasma insulin levels, 2) higher insulin response to OGTT, 3) a decrease in insulin response to OGTT after naloxone administration, with significant differences at 60 min (p less than 0.01) and 90 min (p less than 0.025). In none of the subjects significant differences were observed in blood glucose levels after OGTT plus naloxone administration. These data suggest that increased endogenous opiates may affect insulin response to glucose in obese with impaired or normal oral glucose tolerance test. At present there seems to be no satisfactory explanation for unchanged blood glucose levels during OGTT with and without naloxone despite a decrease in insulin secretion in the obese patients.     

Combined effects of short-term calorie restriction and exercise on insulin action in normal rats

The present study examined the effect of combination of short-term calorie restriction (CR) and moderate exercise on insulin action in normal rats. Rats were divided randomly into 4 groups: ad libitum, sedentary (A-Sed); calorie restriction, sedentary (CR-Sed); ad libitum, exercise (A-Ex); and calorie restriction, exercise (CR-Ex). Rats in the exercise groups were run on a rodent treadmill. Rats in the CR groups were fed every alternate day. Oral glucose tolerance test (OGTT) showed improvements in both CR-Sed and A-Ex groups compared with the A-Sed group; no further improvement in glucose tolerance was observed in the CR-Ex group. In contrast, glucose infusion rates (GIRs) determined by the hyperinsulinemic-euglycemic clamp method indicated that the GIR of the CR and exercise combination was significantly better than that of the sole intervention of CR or exercise. There was no difference in the levels of fasting glucose, insulin, or high-molecular weight forms of adiponectin among the 4 groups. Protein expression of GLUT-4 in the skeletal muscle increased by exercise, but not by CR. Our findings indicate that the combination of exercise and CR may be effective in enhancing insulin sensitivity at the skeletal muscle in normal subjects.     

The effect of prior exercise on oral glucose tolerance in late gestational women

Glucose tolerance deteriorates over the course of a normal human pregnancy as a result of increased peripheral insulin resistance. In contrast, physical exercise has been shown to improve glucose tolerance and blunt the insulin response to a glucose load in insulin-resistant individuals. The purpose of this study was to determine the effect of exercise on glucose tolerance and the insulin response in healthy women during the third trimester of pregnancy (33 weeks of gestation). Five subjects underwent oral glucose tolerance tests (a) 30 min following a 30-min exercise bout on a cycle ergometer at a relative intensity of 50% maximal aerobic capacity, and (b) on a control day without prior exercise. The area under the glucose concentration curve was not different between trials, while the area under the insulin concentration curve was decreased by 23% in the exercise trial compared with the control trial (P less than 0.05). These results suggest that the insulin response to a glucose load is improved in late gestational women by a single bout of moderate intensity exercise.     

Effect of resistance exercise on dehydroepiandrosterone sulfate concentrations during a 72-h recovery: relation to glucose tolerance and insulin response

Serum dehydroepiandrosterone sulfate (DHEA-S) concentration is known to be associated with the whole-body insulin sensitivity. The main purpose of the study was to investigate the effect of resistance exercise on DHEA-S concentration during a 72 h post-exercise recovery, and its relation to glucose tolerance and insulin sensitivity. Morning fasted serum samples was obtained from 19 male volunteers (aged 21.1+/-0.4 years) 24 h before the onset of exercise and 24 h, 48 h, and 72 h following exercise for measurements of DHEA-S, cortisol, and TNF-alpha. Oral glucose tolerance test (OGTT) and insulin response were determined 24 h before and 48 h after exercise. We found that resistance exercise causes a delayed suppression in serum DHEA-S levels during recovery (48 h and 72 h). This exercise challenge did not affect glucose tolerance, but insulin response during OGTT was significantly elevated. The increased insulin level was not associated with serum levels of cortisol and TNF-alpha. In conclusion, the present study found that resistance exercise has a DHEA-S lowering effect that persisted for 72 h. This change could be related to the elevated insulin concentrations during OGTT.     

Assessment of insulin resistance in normoglycemic young adults

Detection of Insulin resistance (IR) in normoglycemic young subjects before the onset of Impaired Glucose Tolerance (IGT) is of importance as it affords implementation of preventive measures in such high risk subject. Very few studies have specifically evaluated for the presence of IR in younger age group with normal glucose tolerance. The gold standard for investigating and quantifying insulin resistance is the “hyperinsulinemic euglycemic clamp,” the complicated nature of the “clamp” technique, alternatives have been sought to simplify the measurement of insulin resistance. The oral glucose tolerance test (OGTT) is one of the most commonly used methods to evaluate whole body glucose tolerance in vivo. IR and IS values of HOMA-IR, ISI_0–120, QUICKIE mathematical models derived from OGTT have been shown to produce equivalent results as in Euglycemic clamp technique we hypothesized that normoglycemic young adult who are siblings of type II diabetics (SD) probably have higher IR values than the siblings of non diabetics as they are genetically predisposed.