Interrupting prolonged sitting in type 2 diabetes: nocturnal persistence of improved glycaemic control.

Abstract

We aimed to examine the effect of interrupting 7h prolonged sitting with brief bouts of walking or resistance activities on 22h glucose homeostasis (including nocturnal-to-following morning hyperglycaemia) in adults with type 2 diabetes. This study is an extension of a previously published randomised crossover trial, which included 24 inactive overweight/obese adults with type 2 diabetes (14 men; 62 ± 6years) who completed three 7h laboratory conditions, separated by 6-14day washout periods: SIT: (1) prolonged sitting (control); (2) light-intensity walking (LW): sitting plus 3min bouts of light-intensity walking at 3.2km/h every 30min; (3) simple resistance activities (SRA): sitting plus 3min bouts of simple resistance activities (alternating half-squats, calf raises, brief gluteal contractions and knee raises) every 30min. In the present study, continuous glucose monitoring was performed for 22h, encompassing the 7h laboratory trial, the evening free-living period after leaving the laboratory and sleeping periods. Meals and meal times were standardised across conditions for all participants. Compared with SIT, both LW and SRA reduced 22h glucose [SIT: 11.6 ± 0.3mmol/l, LW: 8.9 ± 0.3mmol/l, SRA: 8.7 ± 0.3mmol/l; p < 0.001] and nocturnal mean glucose concentrations [SIT: 10.6 ± 0.4mmol/l, LW: 8.1 ± 0.4mmol/l, SRA: 8.3 ± 0.4mmol/l; p < 0.001]. Furthermore, mean glucose concentrations were sustained nocturnally at a lower level until the morning following the intervention for both LW and SRA (waking glucose both -2.7 ± 0.4mmol/l compared with SIT; p < 0.001). Interrupting 7h prolonged sitting time with either LW or SRA reduced 22h hyperglycaemia. The glycaemic improvements persisted after these laboratory conditions and nocturnally, until waking the following morning. These findings may have implications for adults with relatively well-controlled type 2 diabetes who engage in prolonged periods of sitting, for example, highly desk-bound workers. anzctr.org.au ACTRN12613000576729 FUNDING: : This research was supported by a National Health and Medical Research Council (NHMRC) project grant (no. 1081734) and the Victorian Government Operational Infrastructure Support scheme.