Obesity and diabetes are rising in Africa, led by higher income countries in the north and south.

Diabetes can contribute to early death and lead to health problems such as nerve damage, blindness and amputation. Across Africa, a growing economy and rapid urbanisation have led to a wealthier middle-class, possibly with shifts in diet and physical activity. This has contributed to the increased development of obesity which, together with a genetic susceptibility, increases the risk of diabetes.

Now, in the first detailed analysis of obesity and diabetes in Africa, the Non-communicable Disease Risk Factor Collaboration (NCD-RisC), led by Professor Majid Ezzati from Imperial College London, has analysed trends in obesity and diabetes across Africa between 1980 and 2014.

Together with academics from the South African Medical Research Council (SAMRC), they analysed studies since the 1980s that had looked at body mass index (BMI) in 1.2 million adults and diabetes in 182,000 adults in Africa. The researchers used these data, together with sophisticated statistical methods, to retrace trends in BMI and diabetes for all of Africa’s 53 countries, divided into five regions (central, eastern, northern, southern and western).

They found that the both obesity and diabetes in all African countries is increasing rapidly, with the average BMI increasing from 21.0 to 23.0 kg/m² in men, and from 21.9 to 24.9 kg/m² in women. They also found the average BMI was higher than the global average in northern and southern regions, and lower than the global average in central, eastern, and western regions. Healthy BMI is set between 18.5 and 25 kg/m², and those equalling or exceeding 25 kg/m² are considered overweight. The threshold for obesity is 30 kg/m².

Over the same time period, diabetes prevalence rose from 3.4% in 1980 to 8.5% in 2014 in men, and from 4.1% to 8.9% in women. Similarly to the BMI results, diabetes occurrence was higher than the global average in northern Africa, and lower than the global average in central, eastern and western regions. In southern Africa, diabetes prevalence in women was higher than the global average, but about the same in men.

Co-lead author Dr James Bentham, from Imperial’s School of Public Health, said: “The increases in obesity and diabetes place further pressure on African health systems, which are already struggling to cope with diseases like HIV/AIDs and malaria. As African populations increasingly live to older ages, obesity and diabetes are likely to become more common and require larger responses.”

The authors say the increasing diabetes in northern Africa can be attributed to differences in diet and an increasingly sedentary lifestyle. In southern Africa, the authors attributed the findings to increased urbanisation and lifestyle, particularly in South Africa.

Differences in data availability between regions mean that some countries were underrepresented, for example in central Africa. However, the authors say the correlation between BMI and diabetes across all African regions highlights the crucial role of obesity in type 2 diabetes.

Dr Bentham added: “Our findings are based on the largest dataset ever collected describing these conditions in Africa. As the continent experiences higher burdens of obesity and diabetes, we also need to use better data to track the performance of countries in preventing these conditions.”

“Trends in obesity and diabetes across Africa from 1980 to 2014: an analysis of pooled population-based studies” by NCD Risk Factor Collaboration (NCD-RisC) – Africa Working Group, published 4 June 2017 in International Journal of Epidemiology