Diabetes exerts a considerable toll on the health resources of the developing countries of sub-Saharan Africa. The chronicity of the disease and diabetic complications places an immense burden on people with diabetes and their families.

The landscape of sub-Saharan Africa is dominated by the twin disasters of poverty and HIV infection. While HIV infection and consequent AIDS so dominate the health needs for sub-Saharan Africa, there is only a small proportion of the population reaching ages at which type 2 diabetes becomes a major health concern. In 2007 only 9.9% of the population are 50 years of age or older, and this is expected to increase to only 10.5% by 2025. Thus the effects of HIV and malnutrition combine to greatly reduce the size of groups most at risk for type 2 diabetes. 

At a glance

	2007	2025
Total population (millions)	747	1,088
Adult population (age 20-79, millions)	336	537
Diabetes (20-79 age group)
Regional prevalence (%)	3.1	3.5
Comparative prevalence (%)	3.6	4.5
Number of people with diabetes (millions)	10.4	18.7
Impaired Glucose Tolerance (IGT) (20- 79 age group)
Regional prevalence (%)	7.2	7.5
Comparative prevalence (%)	8.2	9.2
Number of people with IGT (millions)	24.2	40.3

Diabetes and IGT prevalence
It is estimated that there were 10.4 million people with diabetes, or 3.1% of the adult population, in the African Region in 2007 (see Table 1). There are marked discrepancies between the rates of diabetes prevalence among different communities in sub-Saharan Africa. The highest prevalences are among the ethnic Indian population of Tanzania   1  and South Africa   2 . The studies from Tanzania   3   4  (urban:rural ratio of 5:1) and Cameroon   5  (ratio of 2:1) both confirm the marked urban/rural discrepancy in diabetes prevalence, with the consequent likely increases in numbers with diabetes as more people move to urban areas.

The availability of prevalence data for sub-Saharan Africa is very limited, and nearly all the data here were derived from studies from South Africa   6   7   8   9 , Tanzania   3   4 , Ghana   10 , Cameroon   5   11  and Sudan   12 . This meant that data from these studies were applied to populations living up to several thousand kilometres from where the study was undertaken. In the three years since the last edition of the Diabetes Atlas (2003), only two further unpublished studies   9   11  have been made available for this report.

Whereas the previously used Cameroon data   5  indicated a much lower prevalence of urban diabetes than the Ghana data, the new data from Cameroon  11  indicate a very similar diabetes prevalence to that for Ghana, but much lower IGT prevalence. Notwithstanding that Cameroon and Ghana are about 1,000 kilometres apart, and classified by the United Nations (UN)   13  as being in different parts of Africa (central and western, respectively), it was decided to use the average of the results of the two studies to apply to the other African countries in the region.

That the data should need to be extrapolated to such distant and probably dissimilar countries and populations indicates the great need for further epidemiological investigation in the region. Such a need can also be linked with the high proportion of diabetes that has not been previously detected, but found only at the time of surveying. Undiagnosed diabetes accounted for 80% of those with the condition in Cameroon   11 , 70% in Ghana   10  and over 80% of the Tanzania survey   4  (See Known and newly diagnosed diabetes).

The impact of type 2 diabetes is bound to continue if nothing is done to curb the rising prevalence of impaired glucose tolerance, which now varies between 0.9% and 16.5% (see Table 1).