One Bout of Exercise Alters Free-Living Postprandial Glycemia in Type 2 Diabetes

Douglas J. Oberlin; Catherine R. Mikus; Monica L. Kearney; Pamela S. Hinton; Camila Manrique; Heather J. Leidy; Jill A. Kanaley; R. Scott Rector; John P. Thyfault

Disclosures

Med Sci Sports Exerc. 2014;46(2):232-238. 

In This Article

Results

Nine subjects completed the study. Baseline anthropometric characteristics, energy intake, blood chemistry, and aerobic fitness data are shown in Table 2 . Medication usage for the subjects were as follows: 6/9 were taking metformin (biguanides), 9/9 were taking statins, 6/9 were taking ACE inhibitors, 1/9 were taking angiotensin receptor blockers, and 3/9 were taking diuretics.

Figure 1 depicts the order of events for the study. The exercise sessions were all supervised and were performed at an intensity of 60% HRR (similar to 60% V̇O2peak) for 60 min. All subjects performed 60 min of exercise at an average percent heart rate reserve of 58.1±5.5. Table 3 shows that the subjects had a statistically significant increase in both steps and energy expenditure on EX day.

PPG Control

EX lowered average glucose concentration significantly during the first 24-h period compared with SED (EX: 5.98 ± 0.0.49 vs SED: 6.62 ± 0.73 mmol·L−1; P = 0.038), but differences were not observed in day 2 (EX: 6.59 ± 0.78 vs SED: 6.62 ± 0.53 mmol·L−1; P = 0.3). Figure 2 shows the average glucose responses measured every 5 min by CGMS during the entire first 24 h of EX or SED conditions, demonstrating lower circulating glucose levels in the EX versus SED condition.

Figure 2.

Glucose measured every 5 min by CGMS during the first 24-h period. Time points for breakfast (8 a.m.), lunch (1 p.m.), and dinner (6p.m.) are approximate times when subjects consumed the three meals.

Repeated-measures ANOVA revealed a main effect of EX to lower PPG-AUC across all six meals compared with SED (P = 0.015) (Fig. 3A); this lower PPG-AUC was primarily due to the effects seen during day 1. The post hoc analysis between EX and SED at each of the six meals revealed that only meal 2 was significantly lower in the EX compared with SED condition (14% lower; P = 0.04) (Fig. 3A). Although other meals showed trends to be lower in the EX versus SED condition (meal 1 EX is 15% lower than SED, P = 0.08; meal 3 EX is 12.8% lower than SED, P = 0.11; meal 6 EX is 19% lower than SED, P = 0.16), they were not statistically different. In addition, there was also a main effect for the 2-h PPG to be lower during the exercise compared with the SED condition (P = 0.005) (Fig. 3B). However, none of the meals were different between EX and SED after post hoc analysis.

Figure 3.

A. Postprandial glucose area under the curve (PPG-AUC) responses to six meals under EX and SED conditions: main effect of EX to lower PPG-AUC (P = 0.015) across all meals compared with SED; *EX significantly lowered PPG-AUC response at meal 2 (P = 0.04) compared with SED. Data are shown as means ± SE. B. PPG-2 h responses to six meals after EX versus SED conditions: main effect of EX to lower PPG-AUC (P = 0.005) across all meals. Data are shown as means ± SE.

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