Elsevier

The Lancet

Volume 375, Issue 9733, 26 June–2 July 2010, Pages 2254-2266
The Lancet

Seminar
Diabetes in sub-Saharan Africa

https://doi.org/10.1016/S0140-6736(10)60550-8Get rights and content

Summary

In Sub-Saharan Africa, prevalence and burden of type 2 diabetes are rising quickly. Rapid uncontrolled urbanisation and major changes in lifestyle could be driving this epidemic. The increase presents a substantial public health and socioeconomic burden in the face of scarce resources. Some types of diabetes arise at younger ages in African than in European populations. Ketosis-prone atypical diabetes is mostly recorded in people of African origin, but its epidemiology is not understood fully because data for pathogenesis and subtypes of diabetes in sub-Saharan African communities are scarce. The rate of undiagnosed diabetes is high in most countries of sub-Saharan Africa, and individuals who are unaware they have the disorder are at very high risk of chronic complications. Therefore, the rate of diabetes-related morbidity and mortality in this region could grow substantially. A multisectoral approach to diabetes control and care is vital for expansion of socioculturally appropriate diabetes programmes in sub-Saharan African countries.

Introduction

Diabetes affects people worldwide and poses major public health and socioeconomic challenges. The disorder was previously thought to be rare or undocumented in rural Africa, but over the past few decades it has emerged as an important non-communicable disease in sub-Saharan Africa.1, 2, 3 After the introduction of standardised diagnostic criteria,4, 5, 6 King and Rewers7 showed, in 1993, that diabetes in adults was a global disorder and that populations of developing countries, minority groups around the world, and disadvantaged communities in industrialised nations faced the greatest risk. Subsequently, several reports on global estimates and projections8, 9, 10, 11, 12 confirmed the diabetes epidemic and indicated that the numbers of people with diabetes and prevalence of both diabetes and impaired glucose tolerance will rise. The increases are expected to be largest in developing regions of the world because of population ageing and urbanisation.10, 11, 12

Estimates from 2009 by the International Diabetes Federation12 suggest that the number of adults with diabetes in the world will expand by 54%, from 284·6 million in 2010 to 438·4 million in 2030. The projected growth for sub-Saharan Africa is 98%, from 12·1 million in 2010 to 23·9 million in 2030. Impaired glucose tolerance in sub-Saharan Africa is expected to rise by 75·8%, from 26·9 million in 2010 to 47·3 million in 2030. This proportion is more than double the predicted global increase of 37%. The report also highlighted the paucity of data from Africa.

Mortality attributable to diabetes in sub-Saharan Africa is estimated, in 2010, at 6% of total mortality, an increase from 2·2–2·5% in 2000. The absolute and relative mortality rates are highest in the 20–39 year age-group—ie, the most economically productive population.12 30 (61%) of the 49 least developed countries as defined by the UN are in sub-Saharan Africa,13, 14 with some of the lowest incomes per head in the world.

In addition to the present challenges of resource depletion, low-income countries face the double burden of communicable diseases (eg, HIV/AIDS) and non-communicable diseases and their risk factors (eg, diabetes). In this Seminar, we present an overview of the effect of diabetes and the health-care challenges encountered in sub-Saharan Africa.

Section snippets

Type 1 diabetes

Data for epidemiology of type 1 diabetes in sub-Saharan Africa are scarce.1, 2, 3 In published studies, prevalence of the disorder is low: 0·33 per 1000 in Nigerian15 and 0·95 per 1000 in Sudanese16 schoolchildren. Reported incidence was low in Tanzania (1·5 per 100 000 per year)17 and high in Sudan (10·1 per 100 000 per year).18 This large difference could be attributable to methodological discrepancies between studies, or true ethnic dissimilarities, because Tanzanian people are predominantly

Ketosis-prone atypical diabetes

Ketosis-prone atypical diabetes is a clinically specific subtype of diabetes seen mostly in populations of African origin. It is characterised by severe hyperglycaemia, with ketosis or ketoacidosis at diagnosis. Affected individuals have a short-term history of polyuria, polydipsia, and weight loss, which are signs of classic type 1 diabetes but arise in patients with an otherwise type 2 phenotype and profile.52 Within days or weeks after initial insulin treatment, long-lasting insulin-free

Type 1 diabetes

Type 1 diabetes in African people is associated with HLA susceptibility loci, particularly HLA-DR3, HLA-DR4, and HLA-DR3/DR4 heterozygosity, similar to white populations. However, different communities have specificities for some alleles and haplotypes.2, 3, 56, 57 Important associations have been seen with HLA-B8, HLA-B14, and HLA-B8/B14, and a negative link has been noted with HLA-BW42. For MHC class II antigens (HLA-D and HLA-DR loci), a significant association of diabetes with HLA-DR4 and

Age, sex, and family history

The International Diabetes Federation12 estimates that the peak age for onset of diabetes in 2010 is 40–59 years, but by 2030, highest prevalence will be in the oldest age-group (60–79 years). In sub-Saharan Africa, prevalence of diabetes increases with age, with most reports indicating a peak at either 65 years or older22, 27, 31, 32, 33, 36, 37, 39, 40 or 55–64 years.37, 38, 41, 42 Age seems to be a relevant risk factor for diabetes.33, 34, 36, 40 This association suggests that, in Africa,

Type 2 diabetes

Both insulin secretion deficiency (β-cell dysfunction) and insulin resistance are seen in African people with type 2 diabetes.105, 106 In offspring of patients with type 2 diabetes from Cameroon, reduced insulin secretion was noted before onset of diabetes, suggesting that this variable could be a major metabolic predictor of progression to diabetes.107

Insulin resistance is associated with obesity;108 the relation with waist circumference (used as a surrogate marker of abdominal obesity) is,

Organisation

In most African communities, delivery of diabetes care is integrated into the overall national health-care structure. The idea of a specialised diabetes care centre and team is a novelty and, where available, limited funding renders it non-functional.118 Health-care systems in most African countries are state-funded and priority is given to the unfinished agenda of communicable diseases. In most countries, no medical insurance or free national health service is available; therefore, the patient

Perspectives

Africa is facing an epidemic of type 2 diabetes and something has to be done to curb the acceleration in lifestyle changes. The health sector alone cannot accomplish population-wide changes to healthy lifestyles. New strategic relations with groups not typically associated with health—but whose activities have an effect on health—are needed. All African governments should develop and implement national diabetes prevention programmes. Prevention of obesity and type 2 diabetes will necessitate

Search strategy and selection criteria

We searched PubMed with keywords including: “diabetes and Africa”, “diabetes prevalence and Africa”, “risk of diabetes and Africa”, “epidemiology of diabetes and Africa”, “urbanization/urban/rural/migration and diabetes and Africa”, “physical activity and diabetes and Africa”, “genetics of diabetes and Africa”, “mortality and diabetes and Africa”, “HIV and diabetes and Africa”, and “diabetes and … [by each country in Africa]”. We included published peer-reviewed reports and reviews and

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