Sub-Saharan Africa (SSA) has the dubious privilege of being a fertile ground for a diabetes epidemic. It has a population of over 1 billion and one of the fastest rates of urbanization in the world, with countries at varying stages of the epidemiological transition. The WHO global action plan for the prevention and control of NCDs 2013-2020 set out the target for a 0% increase in diabetes by 2020 (1). However, achieving this will remain a pipe-dream unless large-scale population studies are employed to understand the distribution and determinants of diabetes in SSA.
Although data on the epidemiology of diabetes in Africa has increased over the last two decades, it is still limited. Diabetes prevalence is variable, but contrary to previous notions, it is not rare. Although the prevalence is still low in some rural African populations, moderate and even high rates have been reported in some countries and there is now evidence that the prevalence is increasing. The International Diabetes Federation estimates that the number of people with diabetes will increase globally by 55% by 2040, with the greatest increase (140%) expected for the Africa region (2). The moderate-to-high frequency of intermediate hyperglycaemia found in many African populations may also indicate that we are in the early stages of a diabetes epidemic.
The wide variability in the prevalence of diabetes and its associated risk factors, suggests that in SSA, diabetes is due to a complex interaction of environmental and genetic factors, which might differ between populations. We know from studies in other settings that overweight and obesity, an unhealthy diet, physical inactivity, high blood pressure, ethnicity, history of gestational diabetes and poor nutrition during pregnancy are associated with increased risk of developing type 2 diabetes (T2D). However, there is currently a dearth of data on these risk factors as well as the impact of HIV/AIDS, and other potential psycho-social, environmental and genetic risk factors in African populations. There is a clear need for comparable and large-scale epidemiological studies to reliably assess the burden of T2D in SSA (2-4).
To this end, the Human Heredity and Health in Africa (H3A) diabetes study was conceived – it is a multi-country epidemiological study of the prevalence and determinants of T2D in SSA, using an approach that spans public health, epidemiology and genomics (5). The primary study aims to assess the burden and spectrum of T2D in adults across SSA and investigate the environmental and genetic determinants of the disease in these populations. It is currently recruiting participants from 11 sites across 8 countries, with recruitment at hospitals and clinics (cases) and through population based cross-sectional surveys (potential controls). The secondary study, conducted in four of the 11 sites, aims to assess and characterize the presence and severity of diabetic eye disease. Data on lifestyle and behavioral risk factors, anthropometry, glucose levels, serology biomarkers and DNA will be taken from all participants. So far, close to 40% of the 12,000 target sample have been recruited. The results of the study will hopefully provide important insights into the known and potentially novel determinants of T2D in SSA and inform prevention and therapeutic strategies to work towards the WHO target of a 0% increase in diabetes prevalence.
- WHO. Global action plan for the prevention and control of noncommunicable diseases 2013–2020. Geneva, Switzerland: World Health Organization, 2013.
- International Diabetes Federation. IDF Diabetes Atlas 7th Edition. Brussels, Belgium, 2015. Available from: http://www.idf.org/diabetesatlas
- Mbanya JC, Motala AA, Sobngwi E, Assah FK, Enoru ST. Diabetes in sub-Saharan Africa. Lancet. 2010;375(9733):2254-66.
- Peer N, Kengne AP, Motala AA, Mbanya JC. Diabetes in the Africa Region: an update. Diabetes research and clinical practice 2014; 103(2): 197-205
- Ekoru K, Young EH, Adebamowo C, Balde N, Hennig BJ, Kaleebu P, Kapiga S, Levitt NS, Mayige M, Mbanya JC, McCarthy MI, Nyan O, Nyirenda M, Oli J, Ramaiya K, Smeeth L, Sobngwi E, Rotimi CN, Sandhu MS, Motala AA. H3Africa Multi-Centre Study of the Prevalence and Environmental and Genetic Determinants of Type 2 Diabetes in Sub-Saharan Africa. Global Health, Epidemiology and Genomics / Volume 1 / January 2016, e5. DOI: http://dx.doi.org/10.1017/gheg.2015.6