Estimating the prevalence, hospitalisation and mortality from type 2 diabetes mellitus in Nigeria: a systematic review and meta-analysis

Abstract

Background: There is not yet a comprehensive evidence-based epidemiological report on type 2 diabetes mellitus (T2DM) in Nigeria. We aimed to estimate country-wide and zonal prevalence, hospitalisation and mortality rates of T2DM in Nigeria.

Methods: We searched MEDLINE, EMBASE, Global Health, Africa Journals Online (AJOL) and Google Scholar for population and hospital-based studies on T2DM in Nigeria. We conducted a random-effects meta-analysis on extracted crude estimates, and applied a meta-regression epidemiological model, using the United Nations demographics for Nigeria in 1990 and 2015 to determine estimates of diabetes in Nigeria for the two years.

Results: 42 studies, with a total population of 91 320, met our selection criteria. Most of the studies selected were of medium quality (90.5%). The age-adjusted prevalence rates of T2DM in Nigeria among persons aged 20-79 years increased from 2.0% (95% CI 1.9% to 2.1%) in 1990 to 5.7% (95% CI 5.5% to 5.8%) in 2015, accounting for over 874 000 and 4.7 million cases, respectively. The pooled prevalence rate of impaired glucose tolerance was 10.0% (95% CI 4.5% to 15.6%), while impaired fasting glucose was 5.8% (95% CI 3.8% to 7.8%). Hospital admission rate for T2DM was 222.6 (95% CI 133.1 to 312.1) per 100 000 population with hyperglycaemic emergencies, diabetic foot and cardiovascular diseases being most common complications. The overall mortality rate was 30.2 (95% CI 14.6 to 45.8) per 100 000 population, with a case fatality rate of 22.0% (95% CI 8.0% to 36.0%).

Conclusion: Our findings suggest an increasing burden of T2DM in Nigeria with many persons currently undiagnosed, and few known cases on treatment.

Keywords: Nigeria; complications; diabetes; epidemiology; mortality; prevalence.

Figure 1

Flow chart of selection of T2DM studies in Nigeria. AJOL, Africa Journals Online; T2DM, type 2 diabetes mellitus.

Figure 2

Funnel plot showing distribution of selected studies. T2DM, type 2 diabetes mellitus.

Figure 3

Pooled prevalence rate of T2DM in Nigeria.T2DM, type 2 diabetes mellitus.

Figure 4

Pooled prevalence rate of IGT in Nigeria. IGT, impaired glucose tolerance.

Figure 5

Pooled prevalence rate of IFG in Nigeria. IFG, impaired fasting glucose.

Figure 6

Pooled mean FPG concentration in Nigeria. FPG, fasting plasma glucose.

Figure 7

Meta-regression epidemiological modelling showing relationship between prevalence of T2DM and mean age of the population.T2DM, type 2 diabetes mellitus.Note: T2DM prevalence (y), age (x), year (z) and size of the bubble correspond to study sample size. Coefficients of ‘x’ and ‘z’ are ‘0.0899’ and ‘0.125’ for the meta-regressed line, with an intercept of ‘−251’.