Purpose: Elevated postprandial glycemic (PPG) excursions are significant risk factors for cardiovascular disease in type 2 diabetes patients. In this study, we tested if and for how many meals a single bout of exercise would reduce PPG responses to subsequent meals in type 2 diabetes (T2D) patients using a continuous glucose monitor system (CGMS).
Methods: We recruited nine sedentary (<30 min·wk−1 of exercise) individuals with T2D (mean ± SD; body mass index = 36.0 ± 1.1 kg·m−2, age = 60.3 ± 1.0 yr, HbA1c = 6.3% ± 0.2%). The subjects consumed a eucaloric diet (51% carbohydrate, 31% fat, and 18% protein) consisting of three meals, identical in composition, for a 2-d period while wearing a continuous glucose monitor system in two different conditions (exercise [EX], one 60-min bout at 60%–75% of heart rate reserve performed before breakfast), vs a sedentary [SED] condition). We quantified 24-h average glucose, PPG area under the curve (AUC; 4-h glucose AUC after meals), and PPG-2 h (2 h postprandial glucose).
Results: EX significantly reduced average [glucose] during the first 24-h period (P = 0.03). EX caused a reduction in PPG-AUC (P = 0.02) for all of the meals during the 2 d (main effect between conditions). A comparison between the EX and the SED conditions at each meal revealed that EX reduced PPG-AUC after the second meal of day 1 (lunch) (P = 0.04). PPG-2 h was not significantly different between EX and SED.
Conclusions: Although a single EX bout does lower 24-h average [glucose], it only significantly lowered PPG-AUC at the second meal after the bout, suggesting that daily exercise may be needed to most effectively improve PPG at the advent of exercise training in T2D patients.
1Departments of Nutrition and Exercise Physiology and Internal Medicine, University of Missouri, Columbia, MO; 2Division of Cardiology, Duke University Medical Center, Durham, NC; 3Division of Endocrinology, University of Missouri, Columbia, MO; 4Division of Gastroenterology and Hepatology, University of Missouri, Columbia, MO; and 5Harry S Truman Memorial VA Hospital, Columbia, MO
Address for correspondence: John P. Thyfault, Ph.D., Departments of Nutrition and Exercise Physiology and Internal Medicine, Division of Gastroenterology and Hepatology, University of Missouri, Columbia, MO 65201; E-mail: firstname.lastname@example.org.
Submitted for publication March 2013.
Accepted for publication July 2013.