Prevalence and Risk Factors for Diabetes Mellitus in Nigeria: A Systematic Review and Meta-Analysis

Introduction: There has been no nationwide health (diabetes) survey in Nigeria since 1992, when a diabetes mellitus (DM) prevalence of 2.2% was reported. We aimed to determine the prevalence of and risk factors for DM in Nigeria by performing a systematic review and meta-analysis. Methods: We searched Medline, EMBASE, PubMed, PapersFirst, the Cochrane Library, Scopus, Bioline, African Journals Online, Institute of Scientific Information, and Google Scholar from the year 1990 to 2017. Using MeSH headings, the terms "diabetes mellitus," "risk factors," "prevalence," and "Nigeria" as well as variations thereof were searched for. The last search was performed on 26 November 2017. We only included studies that utilized the random plasma glucose test, the fasting plasma glucose test, the oral glucose tolerance test (OGTT), or HbA1c to diagnose DM. A total of 23 studies (n = 14,650 persons) were evaluated. A random effects model was used to estimate the pooled prevalence of DM. We estimated the overall pooled prevalence of DM and subgroup-specific DM prevalences while accounting for inter-study and intra-study variability/heterogeneity. Results: The overall pooled prevalence of DM was 5.77% (95% CI 4.3-7.1). The pooled prevalences of DM in the six geopolitical zones of Nigeria were 3.0% (95% CI 1.7-4.3) in the north-west, 5.9% (95% CI 2.4-9.4) in the north-east, 3.8% (95% CI 2.9-4.7) in the north-central zone, 5.5% (95% CI 4.0-7.1) in the south-west, 4.6% (95% CI 3.4-5.9) in the south-east, and 9.8% (95% CI 7.2-12.4) in the south-south zone. Risk factors for the pooled prevalence of DM were a family history of DM (4.6%; 95% CI 3.5-5.6); urban dwelling (6.0%; 95% CI 4.3-7.8); unhealthy dietary habits (8.0%; 95% CI 5.4-10.5); cigarette smoking (4.4%; 95% CI 1.3-10.2); older age (6.6%; 95% CI 4.5-8.7); physical inactivity (4.8%; 95% CI 3.2-6.4); and obesity (5.3%; 95% CI 3.8-6.9). Conclusion: There has been an increase in the prevalence of DM in Nigeria. All regions of the country have been affected, with the highest prevalence seen in the south-south geopolitical zone. Urban dwelling, physical inactivity, advanced age, and unhealthy diet are important risk factors for DM among Nigerians. A national diabetes care and prevention policy is highly recommended.