Exercise Therapy in Type 2 Diabetes: Is daily exercise required to optimize glycemic control?

OBJECTIVE: Given the transient nature of exercise-induced improvements in insulin sensitivity, it has been speculated that daily exercise is preferred to maximize the benefits of exercise for glycemic control. The current study investigates the impact of daily exercise versus exercise performed every other day on glycemic control in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: Thirty type 2 diabetic patients (age 60 ± 1 years, BMI 30.4 ± 0.7 kg/m(2), and HbA(1c) 7.2 ± 0.2%) participated in a randomized crossover experiment. Subjects were studied on three occasions for 3 days under strict dietary standardization but otherwise free-living conditions. Blood glucose homeostasis was assessed by continuous glucose monitoring over 48 h during which subjects performed no exercise (control) or 60 min of cycling exercise (50% maximal workload capacity) distributed either as a single session performed every other day or as 30 min of exercise performed daily. RESULTS: The prevalence of hyperglycemia (blood glucose >10 mmol/L) was reduced from 7:40 ± 1:00 h:min per day (32 ± 4% of the time) to 5:46 ± 0:58 and 5:51 ± 0:47 h:min per day, representing 24 ± 4 and 24 ± 3% of the time, when exercise was performed either daily or every other day, respectively (P < 0.001 for both treatments). No differences were observed between the impact of daily exercise and exercise performed every other day. CONCLUSIONS: A short 30-min session of moderate-intensity endurance-type exercise substantially reduces the prevalence of hyperglycemia throughout the subsequent day in type 2 diabetic patients. When total work is being matched, daily exercise does not further improve daily glycemia compared with exercise performed every other day.