Effects of eccentric exercise on insulin secretion and action in humans

1993 ◽  
Vol 75 (5) ◽  
pp. 2151-2156 ◽  
Author(s):  
D. S. King ◽  
T. L. Feltmeyer ◽  
P. J. Baldus ◽  
R. L. Sharp ◽  
J. Nespor
Keyword(s):  
Insulin Secretion ◽  
Eccentric Exercise ◽  
Plasma Glucose ◽  
Early Phase ◽  
Pancreatic Beta Cell ◽  
Late Phase ◽  
Insulin Response ◽  
Whole Body ◽  
Glucose Disposal ◽  
Hyperglycemic Clamp

The effects of an exhaustive bout of eccentric exercise on insulin secretion and action were determined using the hyperglycemic clamp technique. Clamps were performed on eight healthy men after 7 days of inactivity and approximately 36 h after a bout of eccentric exercise. Eccentric exercise consisted of 10 sets of 10 repetitions of combined knee extensions and flexions for each leg at a mean torque 84 +/- 5% of peak concentric torque. During the hyperglycemic clamp procedure, plasma glucose concentration was acutely raised to 10 mmol/l and was maintained near this level for 120 min. Arterialized blood samples were obtained from a heated hand vein to determine plasma glucose and insulin concentrations. Eccentric exercise appeared to produce marked muscle damage, as indicated by a 50-fold increase in plasma creatine phosphokinase (100 +/- 17 vs. 5,209 +/- 3,811 U/l, P < 0.001) and subjective reports of muscle soreness. Peak insulin response during the early phase (0–10 min) of the hyperglycemic clamp was higher after eccentric exercise (183 +/- 38 microU/ml) than after the control clamp (100 +/- 23 microU/ml, P < 0.005). Late-phase (10- to 120-min) insulin response was not altered after eccentric exercise. Peak plasma C-peptide concentrations were higher during the early phase (5.0 +/- 0.7 vs. 4.3 +/- 0.8 ng/ml, P < 0.05) and the late phase (7.5 +/- 0.9 vs. 5.4 +/- 0.6 ng/ml, P < 0.05). Prior eccentric exercise had no significant effect on whole body glucose disposal or glucose disposal rate adjusted for prevailing plasma insulin concentration. These data provide evidence that a single bout of eccentric exercise causes an increase in pancreatic beta-cell insulin secretion in response to hyperglycemia.

Effects of treadmill exercise to exhaustion on the insulin response to hyperglycemia in untrained men

1991 ◽  
Vol 70 (1) ◽  
pp. 246-250 ◽  
Author(s):  
J. P. Kirwan ◽  
R. E. Bourey ◽  
W. M. Kohrt ◽  
M. A. Staten ◽  
J. O. Holloszy
Keyword(s):  
Insulin Secretion ◽  
Early Phase ◽  
Pancreatic Beta Cell ◽  
Late Phase ◽  
Insulin Response ◽  
Creatine Kinase Activity ◽  
Whole Body ◽  
Glucose Disposal ◽  
C Peptide ◽  
Hyperglycemic Clamp

The effects of a single bout of exercise to exhaustion on pancreatic insulin secretion were determined in seven untrained men by use of a 3-h hyperglycemic clamp with plasma glucose maintained at 180 mg/100 ml. Clamps were performed either 12 h after an intermittent treadmill run at approximately 77% maximum O2 consumption or without prior exercise. Arterialized blood samples for glucose, insulin, and C-peptide determination were obtained from a heated hand vein. The peak insulin response during the early phase (0–10 min) of the postexercise clamp was higher (81 +/- 8 vs. 59 +/- 9 microU/ml; P less than 0.05) than in the nonexercise clamp. Incremental areas under the insulin (376 +/- 33 vs. 245 +/- 51 microU.ml-1.min) and C-peptide (17 +/- 2 vs. 12 +/- 1 ng.ml-1.min) curves were also greater (P less than 0.05) during the early phase of the postexercise clamp. No differences were observed in either insulin concentrations or whole body glucose disposal during the late phase (15–180 min). Area under the C-peptide curve was greater during the late phase of the postexercise clamp (650 +/- 53 vs. 536 +/- 76 ng.ml-1.min, P less than 0.05). The exercise bout induced muscle soreness and caused an elevation in plasma creatine kinase activity (142 +/- 32 vs. 305 +/- 31 IU/l; P less than 0.05) before the postexercise clamp. We conclude that in untrained men a bout of running to exhaustion increased pancreatic beta-cell insulin secretion during the early phase of the hyperglycemic clamp. Increased insulin secretion during the late phase of the clamp appeared to be compensated by increased insulin clearance.

scholarly journals The relationship between fasting hyperglycemia and insulin secretion in subjects with normal or impaired glucose tolerance

2008 ◽  
Vol 295 (2) ◽  
pp. E401-E406 ◽  
Author(s):  
Muhammad A. Abdul-Ghani ◽  
Masafumi Matsuda ◽  
Rucha Jani ◽  
Christopher P. Jenkinson ◽  
Dawn K. Coletta ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Impaired Glucose Tolerance ◽  
Plasma Glucose ◽  
Early Phase ◽  
Mexican Americans ◽  
Late Phase ◽  
Oral Glucose ◽  
C Peptide ◽  
The Relationship

To assess the relationship between the fasting plasma glucose (FPG) concentration and insulin secretion in normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) subjects, 531 nondiabetic subjects with NGT ( n = 293) and IGT ( n = 238; 310 Japanese and 232 Mexican Americans) received an oral glucose tolerance test (OGTT) with measurement of plasma glucose, insulin, and C-peptide every 30 min. The insulin secretion rate was determined by plasma C-peptide deconvolution. Insulin sensitivity (Matsuda index) was measured from plasma insulin and glucose concentrations. The insulin secretion/insulin resistance (IS/IR) or disposition index was calculated as ΔISR/ΔG ÷ IR. As FPG increased in NGT subjects, the IS/IR index declined exponentially over the range of FPG from 70 to 125 mg/dl. The relationship between the IS/IR index and FPG was best fit with the equation: 28.8 exp(−0.036 FPG). For every 28 mg/dl increase in FPG, the IS/IR index declined by 63%. A similar relationship between IS/IR index and FPG was observed in IGT. However, the decay constant was lower than in NGT. The IS/IR index for early-phase insulin secretion (0–30 min) was correlated with the increase in FPG in both NGT and IGT ( r = −0.43, P < 0.0001 and r = −0.20, P = 0.001, respectively). However, the correlation between late-phase insulin secretion (60–120 min) and FPG was not significant. In conclusion, small increments in FPG, within the “normal” range, are associated with a marked decline in glucose-stimulated insulin secretion and the decrease in insulin secretion with increasing FPG is greater in subjects with NGT than IGT and primarily is due to a decline in early-phase insulin secretion.

Effects of physiologic and supraphysiologic hyperglycemia on early and late-phase insulin secretion in chronically dialyzed uremic patients

1989 ◽  
Vol 121 (2) ◽  
pp. 251-258 ◽  
Author(s):  
Ole Schmitz
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Serum Insulin ◽  
Late Phase ◽  
Insulin Response ◽  
Glucose Disposal ◽  
Insulin Resistant ◽  
Normal Glucose ◽  
Glucose Challenge ◽  
Uremic Patients

Abstract. To test secretory capacity of the beta-cell to a glucose stimulus in uremic patients on chronic dialysis, three hyperglycemic clamps (plasma glucose increments: 1, 4.5 and 11 mmol/l) were performed in 8 uremic and 8 healthy subjects. Early-phase insulin and C-peptide responses (ΔI and ΔC) during the initial 6 min were consistently exaggerated at all three steps in uremic patients compared with controls (ΔI. 16 ± 4 vs 4 ± 2, 41 ± 11 vs 15 ± 4 and 60 ± 12 vs 24 ± 5 mU/l; ΔC. 0.39 ± 0.13 vs 0.07 ± 0.02, 0.40 ± 0.13 vs 0.16 ± 0.02 and 0.73 ± 0.15 vs 0.29 ± 0.04 nmol/l, p < 0.05 in all cases). Similarly, late-phase insulin secretion defined as the insulin increment between 90 and 120 min after initiation of the glucose challenge was enhanced in uremic patients at the two highest glycemic steps (44 ± 10 vs 16 ± 2 and 123 ± 29 vs 44 ± 5 mU/l, both p < 0.01). The raised late-phase insulin response allowed comparable glucose disposal in the two groups (uremic patients: 9.2 ± 1.0 and 15.5 ± 1.6 mg · kg−1 · min−1· Controls: 9.0 ± 1.3 and 19.9 ± 2.4 mg · kg−1 · min−1). The slopes of potentiation, i.e. the slopes of the regression lines expressing the relationship between changes in insulin increments and changes in glucose, were markedly steeper in uremic patients (0.45 ± 0.09 and 0.66 ± 0.20, early and late-phase respectively) than in controls (0.20 ± 0.06 and 0.25 ± 0.03). No relationship between serum insulin responses and electrolytes or PTH was demonstrated. In conclusion, despite several factors which may inhibit the ability of the beta-cell to respond to a glucose stimulus, acute hyperglycemia elicits in insulin-resistant uremic subjects an exaggerated early and late-phase insulin secretion which is able to compensate for insulin resistance, thereby maintaining normal glucose disposal.

scholarly journals A reduced incretin effect mediated by the rs7903146 variant in the TCF7L2 Gene is an early marker of beta-cell dysfunction in obese youth

2020 ◽  
Author(s):  
Alfonso Galderisi ◽  
Domenico Trico ◽  
Bridget Pierpont ◽  
Veronika Shabanova ◽  
Stephanie Samuels ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Sensitivity ◽  
Beta Cell ◽  
Plasma Glucose ◽  
Metabolic Phenotype ◽  
Glucose Disposal ◽  
Incretin Effect ◽  
Tcf7l2 Gene ◽  
Intravenous Glucose ◽  
Hyperglycemic Clamp

<b>Background.</b> The risk genotype for the common variant <i>rs7903146 </i>of the transcription factor-7-like-2 gene (<i>TCF7L2</i>) has been found to affect the incretin response in healthy and obese adults, however, whether a similar functional defect is also present in obese adolescents remains unexplored. Herein, we examined the functional effect of the <i>rs7903146</i> variant in the TCF7L2 gene on the incretin effect and determined its translational metabolic manifestation by performing deep phenotyping of the incretin system, beta-cell function relative to insulin sensitivity, the Gastrointestinal Induced Glucose Disposal (GIGD) in obese youths with normal and impaired glucose tolerance. <p><b>Methods</b> Thirty nine non-diabetic obese adolescents (15[14,18] years; BMI 37[33, 43]kg/m<sup>2</sup>) were genotyped for the <i>rs7903146 </i>of <i>TCF7L2</i> and underwent a 3-hour OGTT followed by an iso-glycemic intravenous glucose infusion (iso-IVGTT) to match the plasma glucose concentrations during the OGTT and a hyperglycemic clamp with arginine stimulation.</p> <p>The incretin effect was measured as 100*(AUC-SR<sub>OGTT </sub>– AUC-SR<sub>iso-IVGTT</sub>)/AUC-SR<sub>OGTT </sub>[AUC-SR=AUC of C-peptide secretion rate]. Participants were grouped into tertiles according to the percentage incretin effect (High-, Moderate- and Low-incretin effect) to describe their metabolic phenotype.</p> <p><b>Results </b>The presence of T risk allele for <i>TCF7L2</i> was associated with a markedly reduced </p> <p>incretin effect compared to the wild type genotype(0.3[-7.2,14] vs 37.8[12.5-52.4], p<0.002) When the cohort was stratified by incretin effect, the High-, Moderate- and Low-incretin groups did not differ with respect to anthropometric features, while the Low-incretin group exhibited higher 1-h glucose (p=0.015), a reduced disposition index, insulin sensitivity and insulin clearance, compared with the High-incretin group. Gastrointestinal induced glucose disposal (GIGD) was reduced in the Low-incretin group (p=0.001). The three groups did not differ with respect to intravenous glucose-induced insulin secretion and arginine response during the hyperglycemic clamp. </p> <p><b>Conclusion </b>A<b> </b> reduced incretin effect and its association with the <i>TCF7L2</i> variant rs7903146 identify an early metabolic phenotype in obese non-diabetic youths, featured by a higher plasma glucose peak at 1hr, lower insulin secretion, sensitivity and clearance, and gastrointestinal glucose disposal. </p>

Effect of 7 days of bed rest on dose-response relation between plasma glucose and insulin secretion

1989 ◽  
Vol 257 (1) ◽  
pp. E43-E48 ◽  
Author(s):  
K. J. Mikines ◽  
F. Dela ◽  
B. Tronier ◽  
H. Galbo
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Insulin Response ◽  
Bed Rest ◽  
Glucose Disposal ◽  
Cell Secretion ◽  
Hyperglycemic Clamp ◽  
Peripheral Insulin Resistance ◽  
Glucose Stimulated Insulin Secretion ◽  
Beta Cell Secretion

Physical training decreases glucose-stimulated insulin secretion. To further explore the influence of the level of daily physical activity on beta-cell secretion, the effect of 7 days of bed rest was studied in six young, healthy men by sequential hyperglycemic clamp technique (7, 11, and 20 mM glucose, each step lasting 90 min). At 11 and 20 mM glucose, insulin concentrations in plasma were higher after (87 +/- 11 and 303 +/- 63 microU/ml) than before (63 +/- 5 and 251 +/- 50 microU/ml, P less than 0.05) bed rest. Also C-peptide levels were higher after bed rest than before during glucose stimulation. The responses of other hormones, metabolites, or electrolytes influencing beta-cell secretion were not influenced by bed rest. In spite of increased insulin levels after bed rest, glucose disposal at 20 mM of glucose was significantly lower after bed rest than before. It is concluded that bed rest for 7 days increases the glucose-stimulated insulin response, at least partly due to a beta-cell adaptation increasing glucose-stimulated insulin secretion. However, the insulin secretion does not increase adequately compared with the peripheral insulin resistance induced by bed rest.

Insulin action and dynamics modelled in patients taking the anabolic steroid methandienone (Dianabol)

1986 ◽  
Vol 71 (6) ◽  
pp. 665-673 ◽  
Author(s):  
I. F. Godsland ◽  
N. M. Shennan ◽  
V. Wynn
Keyword(s):  
Insulin Resistance ◽  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Anabolic Steroid ◽  
Plasma Glucose ◽  
Insulin Response ◽  
Glucose Disposal ◽  
Initial Increase ◽  
Second Phase ◽  
Minimal Models

1. Plasma glucose and insulin concentrations were measured during oral (OGTT) and intravenous (IVGTT) glucose tolerance tests in nine patients off- and on-treatment with the anabolic steroid, methandienone (Dianabol). 2. On-treatment, the tolerance tests showed a markedly increased insulin response accompanied by impairment of glucose tolerance, characteristics normally attributed to insulin resistance. However, fasting plasma glucose (FPG) and insulin (FPI) concentrations were significantly reduced, whereas the pattern normally associated with insulin resistance is for both to be raised. 3. IVGTT glucose and insulin profiles were analysed using an algorithm derived from the minimal models of glucose and insulin dynamics originally proposed by R. Bergman and co-workers. Measures for the following parameters were thus obtained: Si, the sensitivity of glucose disposal to insulin; Sg, net insulin independent glucose disposal; ϕ1, the integral concentration of insulin delivered during the first phase of insulin secretion relative to the initial increase in glucose concentration above a model-derived threshold; ϕ2 the sensitivity of the rate of rise of insulin concentration in the second phase of insulin secretion to the concentration of glucose above a model-derived threshold; κ, the fractional clearance rate of insulin; and tl/2, the insulin half-life. 4. Si was significantly reduced on treatment by a factor of 4. Sg, ϕ1, ϕ2 and t1/2 were all significantly increased, and κ was significantly reduced. The increases in Sg and ϕ1 both showed significant correlations with the increase in weight on-treatment. 5. The reduction in FPG and FPI can be explained by the combined effects of the increase in Sg and Dianabol-induced resistance to glucagon. 6. Application of the Bergman models proved to be of value in identifying and quantifying Dianabol-induced insulin resistance. Model-derived parameters of insulin clearance and net insulin independent glucose uptake were also of use in interpreting the changes in glucose and insulin concentrations observed. However, model-derived parameters of pancreatic insulin secretion were likely to have been confounded by reduced hepatic insulin uptake associated with a state of relative insulin resistance.

scholarly journals A reduced incretin effect mediated by the rs7903146 variant in the TCF7L2 Gene is an early marker of beta-cell dysfunction in obese youth

2020 ◽  
Author(s):  
Alfonso Galderisi ◽  
Domenico Trico ◽  
Bridget Pierpont ◽  
Veronika Shabanova ◽  
Stephanie Samuels ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Sensitivity ◽  
Beta Cell ◽  
Plasma Glucose ◽  
Metabolic Phenotype ◽  
Glucose Disposal ◽  
Incretin Effect ◽  
Tcf7l2 Gene ◽  
Intravenous Glucose ◽  
Hyperglycemic Clamp

<b>Background.</b> The risk genotype for the common variant <i>rs7903146 </i>of the transcription factor-7-like-2 gene (<i>TCF7L2</i>) has been found to affect the incretin response in healthy and obese adults, however, whether a similar functional defect is also present in obese adolescents remains unexplored. Herein, we examined the functional effect of the <i>rs7903146</i> variant in the TCF7L2 gene on the incretin effect and determined its translational metabolic manifestation by performing deep phenotyping of the incretin system, beta-cell function relative to insulin sensitivity, the Gastrointestinal Induced Glucose Disposal (GIGD) in obese youths with normal and impaired glucose tolerance. <p><b>Methods</b> Thirty nine non-diabetic obese adolescents (15[14,18] years; BMI 37[33, 43]kg/m<sup>2</sup>) were genotyped for the <i>rs7903146 </i>of <i>TCF7L2</i> and underwent a 3-hour OGTT followed by an iso-glycemic intravenous glucose infusion (iso-IVGTT) to match the plasma glucose concentrations during the OGTT and a hyperglycemic clamp with arginine stimulation.</p> <p>The incretin effect was measured as 100*(AUC-SR<sub>OGTT </sub>– AUC-SR<sub>iso-IVGTT</sub>)/AUC-SR<sub>OGTT </sub>[AUC-SR=AUC of C-peptide secretion rate]. Participants were grouped into tertiles according to the percentage incretin effect (High-, Moderate- and Low-incretin effect) to describe their metabolic phenotype.</p> <p><b>Results </b>The presence of T risk allele for <i>TCF7L2</i> was associated with a markedly reduced </p> <p>incretin effect compared to the wild type genotype(0.3[-7.2,14] vs 37.8[12.5-52.4], p<0.002) When the cohort was stratified by incretin effect, the High-, Moderate- and Low-incretin groups did not differ with respect to anthropometric features, while the Low-incretin group exhibited higher 1-h glucose (p=0.015), a reduced disposition index, insulin sensitivity and insulin clearance, compared with the High-incretin group. Gastrointestinal induced glucose disposal (GIGD) was reduced in the Low-incretin group (p=0.001). The three groups did not differ with respect to intravenous glucose-induced insulin secretion and arginine response during the hyperglycemic clamp. </p> <p><b>Conclusion </b>A<b> </b> reduced incretin effect and its association with the <i>TCF7L2</i> variant rs7903146 identify an early metabolic phenotype in obese non-diabetic youths, featured by a higher plasma glucose peak at 1hr, lower insulin secretion, sensitivity and clearance, and gastrointestinal glucose disposal. </p>

scholarly journals A reduced incretin effect mediated by the rs7903146 variant in the TCF7L2 Gene is an early marker of beta-cell dysfunction in obese youth

2020 ◽  
Author(s):  
Alfonso Galderisi ◽  
Domenico Trico ◽  
Bridget Pierpont ◽  
Veronika Shabanova ◽  
Stephanie Samuels ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Sensitivity ◽  
Beta Cell ◽  
Plasma Glucose ◽  
Metabolic Phenotype ◽  
Glucose Disposal ◽  
Incretin Effect ◽  
Tcf7l2 Gene ◽  
Intravenous Glucose ◽  
Hyperglycemic Clamp

<b>Background.</b> The risk genotype for the common variant <i>rs7903146 </i>of the transcription factor-7-like-2 gene (<i>TCF7L2</i>) has been found to affect the incretin response in healthy and obese adults, however, whether a similar functional defect is also present in obese adolescents remains unexplored. Herein, we examined the functional effect of the <i>rs7903146</i> variant in the TCF7L2 gene on the incretin effect and determined its translational metabolic manifestation by performing deep phenotyping of the incretin system, beta-cell function relative to insulin sensitivity, the Gastrointestinal Induced Glucose Disposal (GIGD) in obese youths with normal and impaired glucose tolerance. <p><b>Methods</b> Thirty nine non-diabetic obese adolescents (15[14,18] years; BMI 37[33, 43]kg/m<sup>2</sup>) were genotyped for the <i>rs7903146 </i>of <i>TCF7L2</i> and underwent a 3-hour OGTT followed by an iso-glycemic intravenous glucose infusion (iso-IVGTT) to match the plasma glucose concentrations during the OGTT and a hyperglycemic clamp with arginine stimulation.</p> <p>The incretin effect was measured as 100*(AUC-SR<sub>OGTT </sub>– AUC-SR<sub>iso-IVGTT</sub>)/AUC-SR<sub>OGTT </sub>[AUC-SR=AUC of C-peptide secretion rate]. Participants were grouped into tertiles according to the percentage incretin effect (High-, Moderate- and Low-incretin effect) to describe their metabolic phenotype.</p> <p><b>Results </b>The presence of T risk allele for <i>TCF7L2</i> was associated with a markedly reduced </p> <p>incretin effect compared to the wild type genotype(0.3[-7.2,14] vs 37.8[12.5-52.4], p<0.002) When the cohort was stratified by incretin effect, the High-, Moderate- and Low-incretin groups did not differ with respect to anthropometric features, while the Low-incretin group exhibited higher 1-h glucose (p=0.015), a reduced disposition index, insulin sensitivity and insulin clearance, compared with the High-incretin group. Gastrointestinal induced glucose disposal (GIGD) was reduced in the Low-incretin group (p=0.001). The three groups did not differ with respect to intravenous glucose-induced insulin secretion and arginine response during the hyperglycemic clamp. </p> <p><b>Conclusion </b>A<b> </b> reduced incretin effect and its association with the <i>TCF7L2</i> variant rs7903146 identify an early metabolic phenotype in obese non-diabetic youths, featured by a higher plasma glucose peak at 1hr, lower insulin secretion, sensitivity and clearance, and gastrointestinal glucose disposal. </p>

Effects of lack of exercise on insulin secretion and action in trained subjects

1988 ◽  
Vol 254 (5) ◽  
pp. E537-E542 ◽  
Author(s):  
D. S. King ◽  
G. P. Dalsky ◽  
W. E. Clutter ◽  
D. A. Young ◽  
M. A. Staten ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Exercise Training ◽  
Insulin Response ◽  
Whole Body ◽  
Short Term ◽  
Trained Subjects ◽  
C Peptide ◽  
Inactive State ◽  
Hyperglycemic Clamp ◽  
Short Period

We employed the hyperglycemic clamp technique to investigate the effects of short-term inactivity on insulin secretion in nine (8 men, 1 woman) well-trained subjects. A 3-h hyperglycemic clamp (plasma glucose approximately 180 mg/100 ml) was performed approximately 16 h after a usual training bout and again 14 days after stopping exercise training. There was no significant change in body composition during this short period of inactivity. The mean plasma insulin response to an identical glycemic stimulus was 67% higher after 14 days without exercise (45 +/- 7 after vs. 27 +/- 4 microU/ml before stopping exercise training). Marked increases in the early (0-10 min, 150 +/- 28 vs. 101 +/- 15 microU.ml-1.min) and late (10-180 min, 6,051 +/- 1,257 vs. 3,521 +/- 749 microU.ml-1.min) incremental insulin areas were observed as a result of the physical inactivity. Incremental areas for C-peptide were also elevated significantly in the inactive state for early (12 +/- 2.0 vs. 7 +/- 1 ng.ml-1.min) and late (567 +/- 90 vs. 467 +/- 85 ng.ml-1.min) phases. Urinary excretion of C-peptide increased from 12.1 +/- 1.5 ng/240 min in the exercising state to 21.8 +/- 3.6 ng/240 min in the inactive state. Rates of whole body glucose disposal were not different between exercising and inactive states, indicating a large increase in resistance to the action of insulin. These findings indicate that the decreased insulin secretory response to a glucose stimulus in people who exercise regularly is a relatively short-term effect of exercise.

Metabolic fate of plasma glucose during hyperglycemia in impaired glucose tolerance: evidence for further early defects in the pathogenesis of type 2 diabetes

2009 ◽  
Vol 296 (3) ◽  
pp. E440-E444 ◽  
Author(s):  
Syed Bokhari ◽  
Peter Emerson ◽  
Zarmen Israelian ◽  
Anchal Gupta ◽  
Christian Meyer
Keyword(s):  
Plasma Glucose ◽  
Glucose Oxidation ◽  
Glycogen Synthesis ◽  
Insulin Response ◽  
Glucose Disposal ◽  
Second Phase ◽  
Metabolic Fate ◽  
Hyperglycemic Clamp ◽  
Normal Glucose ◽  
Glucose Tolerant

We examined the intracellular metabolic fate of plasma glucose during a hyperglycemic clamp in impaired glucose-tolerant (IGT; n = 21) and normal glucose-tolerant subjects ( n = 10) using a combination of [3-3H]glucose infusion with measurement of [3H]water formation and indirect calorimetry. IGT was associated with ∼35% reduced first-phase insulin responses, normal second-phase insulin response, and 25–30% reduced insulin sensitivity, resulting in ∼35% reduced plasma glucose disposal. This was coupled with ∼55% reduced storage of plasma glucose ( P < 0.01) and ∼15–20% reduced glycolysis of plasma glucose ( P < 0.03), accounting for ∼75 and 25% of the reduction in glucose disposal, respectively. Decreased glucose oxidation accounted for virtually all the decrease in glycolysis. Therefore, nonoxidative glycolysis of plasma glucose in IGT was similar to that in NGT ( P > 0.9) and accounted for an increased proportion of systemic glucose disposal ( P < 0.05). We conclude that, in IGT, decreased disposal of plasma glucose involves mainly decreased glycogen synthesis and to a lesser extent decreased glycolysis, which is accounted for by decreased glucose oxidation. An increased proportion of plasma glucose hence undergoes nonoxidative glycolysis, representing a novel early abnormality in the pathogenesis of T2DM.

Sign in / Sign up

Export Citation Format

Share Document