Systematic review on the prevalence of diabetes, overweight/obesity and physical inactivity in Ghanaians and Nigerians

Summary

Objective

To review the prevalence of diabetes, obesity and physical inactivity among Ghanaians and Nigerians in Africa, Europe and North America.

Methods

This systematic literature review used MEDLINE 1966–2005, EMBASE 1980–2005 and cited references to identify relevant studies on Ghanaians and Nigerians.

Results

No studies on Ghanaians or Nigerians in Europe or North America have been reported. Sixteen studies in Africa were included; 13 on Nigerians and three on Ghanaians. The data were limited, poorly reported and not easily comparable. Pooled analysis was not possible. Precise time trend analysis was not possible, but diabetes seemed rare at 0.2% in urban Ghana in 1963 and 1.65% in urban Nigeria in 1985. The prevalence of diabetes in Nigerian adults (age ⩾40 years) in 2000 was 6.8% [confidence intervals (CI) 4.6–9.0]. In Ghana, the prevalence of diabetes in adults (age ⩾25 years) was 6.3% (CI 5.6–7.0) in 1998. Obesity (body mass index ⩾30) among Nigerian adults was 8.8% (CI 7.0–10.6) in 2000, and obesity in Ghanaian adults (⩾25 years) was 14.1% (CI 13.1–15.1%) in 1998. Various studies reported that 25–57% of Nigerians were physically inactive.

Conclusion

Although weak, the evidence base points to a rise in diabetes prevalence in Ghana and Nigeria, with major urban–rural differences. There is an urgent need for accurate and comparable surveys on diabetes and its risk factors among Nigerians and Ghanaians. Effective public health policies are vital to control the diabetes epidemic.

Introduction

Globally, the burden of type 2 diabetes is rising fast. The global prevalence of diabetes among adults was estimated at 150 million in 1995, and this is projected to increase to 300 million by 2025.¹ Developing countries including sub-Saharan Africa may experience the largest proportional increase in diabetes.² The International Diabetes Federation has reported that the annual healthcare cost of diabetes globally for adults (20–79 years old) is 153 billion international dollars. This value is expected to increase to 396 billion international dollars by 2025.³ As recently as 30–40 years ago, the prevalence of diabetes in West Africans was considered to be negligible.4, 5, 6, 7 However, it appears that diabetes is rising rapidly in Africa. The International Collaboration Study of Hypertension in Blacks reported a high prevalence of diabetes and its risk factors among people of West African origin living in middle- and high-income countries compared with those living in African countries.8, 9 Such studies signal what is to come in Africa as changes in lifestyle accompany economic progress.¹⁰ This study systematically reviewed the prevalence of diabetes, impaired glucose tolerance (IGT) and two modifiable risk factors (obesity/overweight and physical inactivity) in Ghanaians and Nigerians. These two countries were chosen because they are major English-speaking West African countries, and because their people exhibit similar sociodemographic characteristics as well as political and historic backgrounds. As well as its scientific aim, the work was undertaken to help health policy makers to assess the priority of diabetes for future research and service delivery. In fact, a number of related reviews have recognized the need for more research and surveys on this and related subjects in Africa. A key finding of this review was that the limited existing data sources used incomparable and non-standardized methods.