Physicians' Academy for Cardiovascular Education

Interrupting sitting time as a means to improve glucose metabolism in T2DM

Breaking sitting with light activities vs structured exercise: a randomised crossover study demonstrating benefits for glycaemic control and insulin sensitivity in type 2 diabetes.

Literature - Duvivier BM, Schaper NC, Hesselink MK et al., - Diabetologia. 2016. doi:10.1007/s00125-016-4161-7

Background

Moderate- to vigorous-intensity exercise is important in the prevention and treatment of type 2 diabetes (T2DM) [1,2], but over 90% of healthy adults do not adhere to the recommendation of current guidelines to do at least 150 min/week of exercise [3]. Non-compliance may be even higher in those with T2DM-related comorbidities such as muscle weakness and peripheral neuropathy, which can be a barrier to physical activity. Alternatives to exercise are therefore needed.

Results of recent observational studies suggest an association between sedentary time and risk of T2DM, independent of the time spent exercising [4,5]. Experimental studies in laboratory conditions suggest that regular interruption of sitting with small bouts of walking may lower glucose and insulin levels in healthy and overweight/obese adults and in those with T2DM [6-10]. In free-living conditions, it has been shown that replacing sitting time with standing and light-intensity walking was more efficient at improving insulin action than replacement with one bout of moderate- to vigorous-intensity exercise in healthy sedentary participants [11].

This study investigated whether these findings could be replicated in those with T2DM, by breaking up sitting time with standing and light-intensity walking and comparing it with structured exercise, under conditions of comparable energy expenditure. Adults with T2DM who exercised less than 2.5 hours/week were instructed to discontinue lipid-lowering drugs and cholesterol-lowering margarines 14 days prior to starting the first regimen.

In a cross-over design, participants followed three activity regimes ‘sitting’ (max 1 hour walking and 1 hour standing per day), ‘exercise’ (1 hour supervised cycling per day) and ‘sit less’ (5 h/day sitting replaced with 2 h walking and 3 h standing, and breaking up sitting time, preferably every 30 min), each for 4 days in free-living conditions. Adherence to the regimens was monitored with an advanced accelerometer. A wash-out period between the successive activity regimes was applied. The order of the intervention was randomised. It was calculated that 19 participants were needed to detect a mean difference of 1.7 mmol/l in 24 h glucose between the activity regimens, with a power of 80%.

Main results

Conclusion

These data show that the Sit Less regimen improved insulin sensitivity, mean 24 h glucose levels, 24h glucose excursions, duration of hyperglycaemia and fasting triacylglycerol levels. In this study, the general effect of the Sit Less regimen on glucose homeostasis tended to be a little more potent than the effect of structured exercise. Insulin sensitivity was more improved after the Sit Less regimen than after the Exercise regimen. In this respect is it interesting to note that during the Exercise regimen participants spent most of the day sitting. It is thus proposed that the duration of non-sitting activities may be more important than the intensity of these activities.

The volume of light-intensity activities in this study was relatively high as compared with what is generally observed in T2DM patients, thus future studies may establish what activity regimen might be more feasible.

References

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