The effect of urbanization on adiposity and insulin resistance among Indonesian

Abstract

Background: The prevalence of obesity and type 2 diabetes (T2DM) in Indonesia is increasing. One of the major socio-environmental factors that might contribute to this is urbanization, which is associated with changes into more sedentary lifestyle and unhealthy diet. These changes can lead to obesity. The metabolic risks of obesity are mainly determined by the body fat content. The higher the body fat content the higher insulin resistance and hence susceptibility of T2DM. The contribution of adiposity to urban-rural differences of insulin resistance in Indonesia is currently unknown. Aim: Our study aims to characterize the differences in adiposity and insulin resistance among urban and rural Indonesian, and to explore the time effects of urbanization. Methods: We recruited 36 adult male participants with Flores ethnicity from a rural area of Ende (Flores) and 36-age-sex-ethnic matched participants from an urban area (Jakarta) who had already moved to Jakarta between 1 and 41 years. We measured body mass index [BMI (kg/m2)], waist circumference [WC (cm)], waist-hip ratio (WHR), 4-sites skinfold [biceps SF, triceps SF, supra iliac SF, subscapular SF (cm)], body fat composition (BIA), fasting glucose (mmol/L), fasting insulin (IU/L), 2h-glucose post 75g glucose load [PPG (mmol/L)], HbA1c (%) and insulin resistance (HOMA-IR). Results: Urban group has significantly higher BMI [24.5(4.7) vs 22.3(4.1); P=0.042], WC [84.9(13.4) vs 77.6(11.2); P=0.014], WHR [0.99(0.062) vs 0.93(0.058); P=0.000] and subscapular SF [16.9(9.0) vs 12.1(7.4); P=0.016]. These differences translate into significantly higher PPG [7.4(2.6) vs 5.7(1.6); P=0.002] and HbA1c [5.5(0.7) vs 5.1(0.6); P=0.007] among urban group, but no significant difference in HOMA-IR [1.38(1.05–1.76) vs 1.05(0.76–1.40); P=0.173]. After adjusting for age, there are positive correlations between the duration of stay in urban area and markers of adiposity, such as BMI (r=0.553, P=0.014), Fat Percentage (r=0.465, P=0.045), WC (r=0.634, P=0.004); but not with HOMA-IR (r=0.301, P=0.210). Conclusion: The people who move to an urban areas have unfavourable adiposity profile which might put them at higher risk of having insulin resistance and hence T2DM in the future. These profile differences are correlated with the duration of stay in the urban area.