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Post-Prandial Glucose Levels Are Elevated by Metformin after High Intensity Exercise Training in Metabolic Syndrome
Steven K Malin1,2,3,4,5,6, Emily M Heiston1, Daniel J Battillo1
1Department of Kinesiology and Health, Rutgers University, New Brunswick, NJ.
Purpose:
The clinical implications of metformin attenuating the insulin sensitizing effects of exercise are unclear. We tested the hypothesis that metformin would blunt reductions in post-prandial glucose in an exercise intensity-based manner in adults with metabolic syndrome (MetS) risk.
Methods:
In a double-blind trial, participants were randomized to low intensity exercise plus placebo (~55%VO2max 5d/wk, LoEx+PL, n=22) or metformin (2000mg/d, LoEx+Met, n=21) and high intensity exercise plus placebo (~85%VO2max 5d/wk, HiEx+PL, n=24) or metformin (HiEx+Met, n=24) for 16 weeks. A 120-min 75g oral glucose tolerance test was conducted pre- and post-treatment to assess early (0-30min), late (60-120min), and total (0-120min) phase glucose tolerance and circulating insulin (total area under the curve; tAUC).
Results:
HiEx+Met increased 1-hr and 2-hr glucose by ~18-21mg/dl (P<0.04), and this was different from HiEx+PL (both, P=0.008). Late phase and total phase glucose tAUC was also higher after HiEx+Met versus HiEx+PL and LoEx+PL (both, P<0.02). Only total phase insulin tAUC was lower after HiEx+Met versus HiEx+PL and LoEx+PL (both, P<0.04). Increased metabolic insulin sensitivity related to reduced late and total phase glucose tAUC (both, P<0.04) after exercise training only.
Conclusions:
Metformin increased post-prandial glucose after high, but not low, intensity exercise training in adults with MetS risk.
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