Reducing sedentary behaviour is potentially an achievable intervention to improve glycaemic control in older adults with type 2 diabetes. However, lower glucose levels have mainly been reported with large reductions in sedentary behaviour (1). We determined the relationship between 24-h movement behaviour and glycaemic variables and quantified how theoretical reallocations of time between behaviours were associated with differences in these measures.
This is a secondary analysis of 24 adults with type 2 diabetes (age 70±5 years, 15 females) in a prospective study. Interstitial glucose was measured using an iPro2 continuous glucose monitoring system (Medtronic/Minimed, USA) and physical activity with a thigh-worn activPAL3 inclinometer (PAL Technologies, Scotland) for two 6-day periods before and after a 6-week incremental goal-setting intervention designed to reduce sedentary behaviour. Compositional isometric log ratios were generated for mean 24-hour sleeping, sitting, standing and stepping time and regressed against mean glucose, time in glucose range (TIGR, glucose 4-10 mmol/L) and mean daily standard deviation for glucose (glucose SD) to determine the association between glycaemic variables and a 30-minute change in behaviours.
Participants spent 8.4±1.4 h/day sleeping, 10.5±2.0 h/day sitting, 3.7±1.7 h/day standing and 1.4±0.5 h/day stepping. Mean glucose was positively associated with sitting with a 30-minute reduction in sitting time associated with a 0.12 mmol/L (95% confidence intervals 0.02-0.21) reduction in mean glucose. A 30-minute reduction in sitting was associated with a 1.5% (0.3-2.6) increase and a 30-minute increase in stepping associated with a 5.7% (1.0-10.4) increase in TIGR. A 30-minute increase in stepping was associated with a 0.31 mmol/L (0.11-0.52) reduction in glucose SD.
Less sitting time is associated with a small reduction in mean glucose and increase in TIGR. More stepping time is associated with a larger increase in TIGR and reduced glycaemic variability and is likely to have a greater beneficial effect on glycaemic control.