Effect of exercise on postprandial insulin responses in Mexican American and non-Hispanic women

Whey protein improves glycemia during an oral glucose tolerance test compared to vigorous-intensity aerobic exercise in young adult men

Background

Both aerobic exercise and whey protein can improve glucose regulation. The purpose of this study was to investigate how a single bout of vigorous-intensity aerobic exercise and whey protein, independently, as well as when combined, influence glycemia during an oral glucose tolerance test in sedentary, young men.

Methods

Healthy males (n = 11) completed four randomized trials: no exercise/no whey protein (R); exercise (EX; walking at 70% VO_2max for 60 min); 50 g of whey protein (W); and exercise combined with 50 g of whey protein (EXW). Each trial included a 75 g oral glucose tolerance test (OGTT) that was completed after an overnight fast. Blood samples were collected over a two-hour period during the OGTT. For EX and EXW, the exercise was performed the evening before the OGTT and the 50 g of whey protein was dissolved in 250 mL of water and was consumed as a preload 30 min prior to the OGTT. For R and EX, participants consumed 250 mL of water prior to the OGTT. Plasma samples were analyzed for glucose, insulin, C-peptide, glucagon, gastric inhibitory peptide (GIP) and glucagon like peptide 1 (GLP-1), and postprandial incremental area under the curve (iAUC) was calculated for each.

Results

Glucose iAUC was reduced during W (− 32.9 ± 22.3 mmol/L) compared to R (122.7 ± 29.8 mmol/L; p < 0.01) and EX (154.3 ± 29.2 mmol/L; p < 0.01). Similarly, glucose iAUC was reduced for EXW (17.4 ± 28.9 mmol/L) compared to R and EX (p < 0.01 for both). There were no differences in iAUC for insulin, C-peptide, GIP, GLP-1, and glucagon between the four trials. Insulin, C-peptide, glucagon, GIP, and GLP-1 were elevated during the whey protein preload period for W and EXW compared to EX and R (p < 0.01). There were no differences for insulin, C-peptide, glucagon, GIP, or GLP-1 between trials for the remaining duration of the OGTT.

Conclusions

Glucose responses during an oral glucose tolerance test were improved for W compared to EX. There were no additional improvements in glucose responses when vigorous-intensity aerobic exercise was combined with whey protein (EXW).

Consecutive days of exercise decrease insulin response more than a single exercise session in healthy, inactive men

PURPOSE

It is reported that a single bout of exercise can lower insulin responses 12-24 h post-exercise; however, the insulin responses to alternate or consecutive bouts of exercise is unknown. Thus, the purpose of this study was to examine the effect of exercise pattern on post-exercise insulin and glucose responses following a glucose challenge.

METHODS

Ten male participants (n = 10, mean ± SD, Age 29.5 ± 7.7 years; BMI 25.7 ± 3.0 kg/m²) completed three exercise trials of walking for 60 min at ~ 70% of VO_2max. The trials consisted of: three consecutive exercise days (3CON), three alternate exercise days (3ALT), a single bout of exercise (SB), and a no exercise control (R). Twelve to fourteen hours after the last bout of exercise or R, participants completed a 75 g oral glucose tolerance test (OGTT) and blood was collected at 30 min intervals for the measurement of glucose, insulin, and C-peptide.

RESULT

Calculated incremental area under the curve (_iAUC) for glucose and C-peptide was not different between the four trials. Insulin _iAUC decreased 34.9% for 3CON compared to R (p < 0.01).

CONCLUSION

Three consecutive days of walking at ~ 70% VO_2max improved insulin response following an OGTT compared to no exercise. It is possible, that for healthy males, the effect of a single bout of exercise or exercise bouts separated by more than 24 h may not be enough stimulus to lower insulin responses to a glucose challenge.

Effectiveness of workplace diabetes prevention programs: A systematic review of the evidence

PURPOSE

The primary purpose is to review diabetes workplace interventions and the degree to which they improve diabetes-related outcomes in employees diagnosed with or at risk for T2DM.

METHODS

Three electronic databases and ancestry searches were used to identify peer reviewed articles published in English from 2000 to June 2017.

RESULTS

The number of participants represented by the 22 selected studies, excluding one large outlier, was 4243. On average, the samples were 57% female and ethnically diverse. Interventions-healthy eating behaviors, physical activity, and/or monitoring and self-managing diabetes and cardiovascular risk factors-were delivered in group sessions of fewer than 20 employees. Programs involved 1-h weekly sessions held during lunch hour or at other times during the workday for 12 to 24 weeks. Study outcomes, commonly measured at 6 and/or 12 months, were consistently positive.

CONCLUSION

The literature search uncovered beginning evidence that workplace interventions hold promise for preventing diabetes and/or its complications. More rigorous, creatively designed, workplace studies, are needed for employees at high-risk for developing diabetes.

PRACTICE IMPLICATIONS

Implications include the need for employer education about the benefits of employer support for such programs and attention to motivational strategies so employees will take full advantage of programs that are offered.

Physical activity, fitness and cardiovascular disease risk in adults: interactions with insulin resistance and obesity

There is a considerable body of evidence gathered from studies over the past half a century indicating that a high level of physical activity and a moderately high or high degree of cardiorespiratory fitness reduces the risk of CVD (cardiovascular disease). Recent data suggest that high levels of physical activity or fitness may be particularly beneficial to individuals with insulin-resistant conditions, such as the metabolic syndrome, Type II diabetes or obesity. These individuals, if unfit and sedentary, exhibit increased CVD risk, but their dose-response relationship for physical activity/fitness appears to be particularly steep such that, when they undertake high levels of activity (or have high fitness), their level of risk becomes closer to that of their normal weight or nondiabetic peers. This may be due to effects of physical activity in normalizing the metabolic dysfunction particularly associated with insulin-resistant conditions.

Effects of oral contraceptives on glucoregulatory responses to exercise

Some of the effects of oral contraceptives (OCs) to alter glucoregulation may be ameliorated by exercise. To test this premise, the effects of acute aerobic exercise on postprandial glucose, insulin, and C-peptide responses (area under the curve [AUC]) were measured in 8 users of low-dose estrogen and progestin OCs (OC(+)) and 10 women not using OCs (OC(-)). They completed 2 randomly ordered intervention trials: (1) aerobic exercise on 3 consecutive days with a 2.5-hour, 75-g oral glucose tolerance test (OGTT) on day 4, and (2) no exercise for 3 days prior to the OGTT (control trial). The exercise was 50 minutes of treadmill walking at 70% (.-)VO(2max). The groups were similar in age (27 +/- 3 years), waist-to-hip ratio (0.74 +/- 0.01), and cardiorespiratory fitness (32.5 +/- 1.6 mL x kg body mass(-1) x min(-1)). Fasting plasma glucose, C-peptide, and insulin levels were similar (P >.05) between groups in the control trial. In both trials, glucose(AUC) was significantly greater (13%, P <.05) in OC(+). Exercise resulted in a significant (P <.05) decrease in fasting plasma glucose and insulin, insulin(AUC), glucose(AUC) x insulin(AUC), and C-peptide(AUC) in both groups, suggesting enhanced insulin action and/or reduced pancreatic insulin secretion. Hepatic insulin extraction ([C-peptide(AUC) - insulin(AUC)())]/C-peptide(AUC)) was increased following exercise only in OC(+). Thus, insulin action was enhanced in response to exercise in young sedentary women independent of OC use. The mechanisms for the acute exercise effect on insulin action may be different in OC users compared with normally menstruating women.