OBJECTIVETo evaluate the feasibility of free-living walking training in type 2 diabetic patients and to investigate the effects of interval-walking training versus continuous-walking training upon physical fitness, body composition, and glycemic control.RESEARCH DESIGN AND METHODSSubjects with type 2 diabetes were randomized to a control (n = 8), continuous-walking (n = 12), or interval-walking group (n = 12). Training groups were prescribed five sessions per week (60 min/session) and were controlled with an accelerometer and a heart-rate monitor. Continuous walkers performed all training at moderate intensity, whereas interval walkers alternated 3-min repetitions at low and high intensity. Before and after the 4-month intervention, the following variables were measured: VO2max, body composition, and glycemic control (fasting glucose, HbA1c, oral glucose tolerance test, and continuous glucose monitoring [CGM]).RESULTSTraining adherence was high (89 ± 4%), and training energy expenditure and mean intensity were comparable. VO2max increased 16.1 ± 3.7% in the interval-walking group (P < 0.05), whereas no changes were observed in the continuous-walking or control group. Body mass and adiposity (fat mass and visceral fat) decreased in the interval-walking group only (P < 0.05). Glycemic control (elevated mean CGM glucose levels and increased fasting insulin) worsened in the control group (P < 0.05), whereas mean (P = 0.05) and maximum (P < 0.05) CGM glucose levels decreased in the interval-walking group. The continuous walkers showed no changes in glycemic control.CONCLUSIONSFree-living walking training is feasible in type 2 diabetic patients. Continuous walking offsets the deterioration in glycemia seen in the control group, and interval walking is superior to energy expenditure–matched continuous walking for improving physical fitness, body composition, and glycemic control.

Despite a ~45% lower training volume, HIIT resulted in similar or even better improvements in physical fitness, body composition and glycemic control compared to END. HIIT therefore appears to be an important time-efficient treatment for individuals with type 2 diabetes.