Incident type 2 diabetes and its risk factors in men and women aged 40–60 years from four sub-Saharan African countries: results from the AWI-Gen study
Raylton P. Chikwati, Nigel J. Crowther, Michèle Ramsay, Lisa K. Micklesfield, Shane A. Norris, Kagiso Peace Seakamela, Engelbert A. Nonterah, Godfred Agongo, Shukri F. Mohamed, Isaac Kisiangani, Palwendé Romuald Boua, Alisha N. Wade, Alisha N Wade, Raylton P Chikwati, Raylton P Chikwati, Nigel J Crowther, Michèle Ramsay, Lisa K Micklesfield, Shane A Norris, Kagiso P Seakamela, Engelbert A Nonterah, Godfred Agongo, Shukri F Mohamed, Isaac Kisiangani, Palwendé Romuald Boua, Alisha N. Wade
Abstract
BACKGROUND: The incidence of type 2 diabetes in sub-Saharan Africa is expected to increase, but few longitudinal studies have characterised its risk factors. This study aimed to determine the incidence of type 2 diabetes over 33 481 person-years and identify its principal risk factors in middle-aged adults (ie, those aged 40-60 years) from four sub-Saharan African countries. METHODS: Longitudinal data were available from 6553 participants aged 40-60 years at baseline from study centres in South Africa, Kenya, Ghana, and Burkina Faso. Sociodemographic, behavioural, clinical, and biochemical data were collected at baseline and after an interval of 5-6 years. The prevalence of type 2 diabetes was determined at each timepoint and diabetes incidence was calculated. A two-stage individual participant data meta-analysis was used to identify baseline risk factors for incident diabetes. FINDINGS: The overall incidence of type 2 diabetes was 14·6 (95% CI 13·4-16·0) cases per 1000 person-years. The incidence was highest in South Africa with 21·8 (19·5-24·4) cases per 1000 person-years, and lowest in west Africa with 5·5 (4·4-6·9) cases per 1000 person-years. Baseline glucose (adjusted odds ratio 1·37; 95% CI 1·16-1·42), being male (1·32; 1·12-1·54), family history of type 2 diabetes (1·22; 1·01-1·46), unemployment (1·19; 1·03-1·37), hypertension (1·21; 1·01-1·45), BMI (1·03; 1·02-1·04), and waist circumference (1·02; 1·01-1·03), were associated with a higher risk of incident type 2 diabetes, while adequate baseline physical activity (0·87; 0·76-1·00) was associated with lower risk. INTERPRETATION: The high incidence of type 2 diabetes in this middle-aged sub-Saharan Africa population is influenced by several modifiable risk factors that should inform interventions to mitigate the disease burden. FUNDING: National Institutes of Health, Department of Science and Innovation (South Africa), and the South African Medical Research Council.