The association between various biological, behavioural and psychosocial factors and type 2 diabetes mellitus in Africa: a systematic review and meta-analysis

Abstract Background Type 2 diabetes mellitus (T2DM) is a significant public health concern in many African countries. While the determinants underpinning T2DM are likely to be Africa-specific, knowledge of these risk factors is largely derived from developed countries. This is the first systematic review and meta-analysis to include biological, behavioural and psychosocial risk factors for T2DM in Africa. Methods Relevant scientific databases were searched, and data were extracted from 66 studies. Fifty- nine studies reported unadjusted data and were analysed using Comprehensive Meta-Analysis (CMA) software version 2.0. The Odds ratios (OR) and their 95% CIs for the associations between BMI indices (overweight, obesity), central obesity (waist circumference, waist to hip ratio), behavioural (alcohol, fruit and vegetable consumption, smoking), physical inactivity, and psychosocial factors (stress, anxiety, and depression) and T2DM were calculated using a random-effect model. Moderator effects of age, language-spoken, sub-regions and urban/rural location was assessed. Results A number of risk factors were associated with T2DM including, BMI-based definitions of obesity [OR = 3.22, 95% CI: 92.73, 3.80)], overweight [OR = 2.22, 95% CI: (1.90, 2.58)], or overweight/obesity [OR = 2.58, 95% CI: (1.76, 3.78)]; Central obesity as measured by waist circumference [OR = 2.51, 95% CI: (1.86, 3.37)], or waist to hip ratio [OR = 2.03, 95% CI: 1.51, 2.72]; psychosocial factors which includes stress [OR = 2.2, 95% CI: (1.46, 3.31)], depression [OR = 2.42, 95% CI: (1.14, 3.31)] and anxiety [OR = 2.05, 95% (CI:1.0, 4.18)] and physical inactivity [OR = 1.88, 95% CI: (1.53, 2.23)]. Current smoker [OR = 1.13, 95% CI: (0.84, 1.49)], alcohol consumption [OR = 1.10, 95% CI: (0.82, 1.47)] and inadequate fruit and vegetable consumption [OR = 0.81, 95% CI: (0.57, 1.16)] were not associated with T2DM. Locality (urban/rural), language spoken, and sub-region (East/West Africa) did not significantly moderate the associations between the risk factors and T2DM. Conclusion Obesity (defined by BMI) is most strongly associated with T2DM. Overweight, waist circumference and waist to hip ratio, physical inactivity, psychosocial risk factors defined as stress, depression, anxiety were all significantly associated with T2DM. These findings add novel meta-analyses of associations between diverse individual risk factors and T2DM within the African context.