Aims: To examine the impact of interrupting prolonged sitting with frequent short bouts of light-intensity activity on glycaemic control in people with type 1 diabetes (T1D).

Materials and methods: 32 inactive adults with T1D (aged 27.9±4.7 years, 15 men, diabetes duration 16.0±6.9 years and HbA1c 8.4±1.4% [68±2.3 mmol/mol]) underwent two 7-hour experimental conditions in a randomised crossover fashion with >7-day washout consisting of: uninterrupted sitting (SIT), or, interrupted sitting with 3-minute bouts of self-paced walking at 30-minute intervals (SIT-LESS). Standardised mixed-macronutrient meals were administered 3.5-hours apart during each condition. Blinded continuous glucose monitoring (CGM) captured interstitial glucose responses during the 7-hour experimental period and for a further 48-hours under free-living conditions.

Results: SIT-LESS reduced total mean glucose (SIT 8.2±2.6 vs. SIT-LESS 6.9±1.7 mmol/L, P=0.001) and increased Time in Range (TIR; 3.9-10.0 mmol/L) by 13.7% (SIT 71.5±9.5 vs. SIT-LESS 85.1±7.1 %, P=0.002). Hyperglycaemia (>10.0 mmol/L) was reduced by 15.0% under SIT-LESS (SIT 24.2±10.8 vs. SIT-LESS 9.2±6.4 %, P=0.002), whereas hypoglycaemia exposure (<3.9 mmol/L) (SIT 4.6±3.0 vs. SIT-LESS 6.0±6.0 %, P=0.583) was comparable across conditions. SIT-LESS reduced glycaemic variability (CV%) by 7.8% across the observation window (P=0.021). These findings were consistent when assessing discrete time periods, with SIT-LESS improving experimental and free-living postprandial, whole-day, and night-time glycaemic outcomes (P<0.05).

Conclusions: Interrupting prolonged sitting with frequent short bouts of light-intensity activity improves acute postprandial and 48-hour glycaemia in adults with T1D. This pragmatic strategy is an efficacious approach to reducing sedentariness and increasing physical activity levels without increasing risk of hypoglycaemia in T1D.