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

Aims/hypothesis We aimed to examine the effect of interrupting 7 h prolonged sitting with brief bouts of walking or resistance activities on 22 h glucose homeostasis (including nocturnal-to-following morning hyperglycaemia) in adults with type 2 diabetes. Methods 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± 6 years) who completed three 7 h laboratory conditions, separated by 6–14 day washout periods: SIT: (1) prolonged sitting (control); (2) light-intensity walking (LW): sitting plus 3 min bouts of light-intensity walking at 3.2 km/h every 30 min; (3) simple resistance activities (SRA): sitting plus 3 min bouts of simple resistance activities (alternating half-squats, calf raises, brief gluteal contractions and knee raises) every 30 min. In the present study, continuous glucose mon-itoring was performed for 22 h, encompassing the 7 h labora-tory trial, the evening free-living period after leaving the lab-oratory and sleeping periods. Meals and meal times were standardised across conditions for all participants. Results Compared with SIT, both LW and SRA reduced 22 h glucose [SIT: 11.6 ± 0.3 mmol/l, LW: 8.9 ± 0.3 mmol/l, SRA: 8.7 ± 0.3 mmol/l; p < 0.001] and nocturnal mean glucose con-centrations [SIT: 10.6 ± 0.4 mmol/l, LW: 8.1 ± 0.4 mmol/l, SRA: 8.3 ± 0.4 mmol/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 ± 0.4 mmol/l compared with SIT; p < 0.001). Conclusions/interpretation Interrupting 7 h prolonged sitting time with either LW or SRA reduced 22 h hyperglycaemia. The glycaemic improvements persisted after these laboratory conditions and nocturnally, until waking the following morn-ing. 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. Trial registration: 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.