Physical activity energy expenditure is associated with 2-h insulin independently of obesity among Inuit in Greenland

AIMS: Indigenous populations throughout the Arctic are experiencing a rapid increase in the prevalence of obesity and type 2 diabetes. The role of physical activity in relation to glucose metabolism in Arctic populations is not well studied. We examined the association between objectively measured physical activity energy expenditure (PAEE) and glucose metabolism in a population-based study of adult Inuit in Greenland.

METHODS: Cross-sectional data were collected by combined accelerometry and heart rate monitoring (ACC+HR) among Inuit (18+ years) in Greenland during 2005-2010 (n=1545). PAEE was calculated and the associations with fasting glucose, 2-h glucose, fasting insulin, 2-h insulin concentrations and body composition were analysed by linear regression.

RESULTS: An inverse association between PAEE and fasting insulin, 2-h insulin, 2-h glucose, fat percentage, BMI and waist circumference (WC) was found after adjustments by age and sex. Only the association between PAEE and 2-h insulin remained significant after adjustment by WC (P=0.01), most pronounced at low levels of PAEE indicating a threshold around 35-40kJ/kg/day. No overall linear trend was found for fasting glucose and 2-h glucose.

CONCLUSIONS: This population-based study showed that PAEE was associated with 2-h insulin independently of obesity in an inverse dose-response relation. Insufficient physical activity may contribute to impaired glucose tolerance through a pathway including alterations in obesity and fat distribution. Both obesity and low levels of PAEE may be important contributing risk factors for the increasing prevalence of type 2 diabetes mellitus among Inuit in Greenland, but additional risk factors should be examined in this indigenous population.