Effect of age and sex on the associations between potential modifiable risk factors and both type 2 diabetes and impaired fasting glycaemia among West African adults.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is becoming one of the leading causes of morbidity and mortality worldwide, including among Africans. Knowledge of the association between traditional risk factors and both diabetes and pre-diabetes, and whether these differ by age and sex, is important for designing targeted interventions. However, little is known about these associations for African populations. METHODS: The study used data from WHO STEPS surveys, comprising 15,520 participants (6,774 men and 8,746 women) aged 25-64 years, from 5 different West African countries, namely Burkina Faso (4,711), Benin (3,816), Mali (1,772), Liberia (2,594), and Ghana (2,662). T-test and chi-square tests were used to compare differences in the prevalence of traditional risk factors for both sexes. Multinomial logistic regression was conducted to ascertain the relative risks (RR) and 95% confidence intervals (CI) for both T2DM and impaired fasting glucose (IFG) relating to each risk factor, including obesity [defined by BMI, waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR)], high blood pressure (HBP), fruit and vegetable consumption, physical inactivity, alcohol consumption, and smoking. Models for each of these traditional risk factors and interactions with age and sex were fitted. RESULTS: Factors associated with T2DM and IFG were age, obesity [defined by BMI, WC, WHtR, and WHR], HBP, smoking, physical inactivity, and fruit and vegetable consumption (p < 0.05). Analysis of interaction effects showed few significant differences in associations between risk factors and T2DM according to age or sex. Significant interaction with age was observed for HBP*age and T2DM [RR; 1.20, 95% CI: (1.01, 1.42)) (p = 0.04)], WHtR*age and T2DM [RR; 1.23, 95% CI: (1.06, 1.44) (p = 0.007)] and WHR*age and IFG [RR: 0.79, 95% CI: (0.67, 0.94) (p = 0.006)]. Some interactions with age and sex were observed for the association of alcohol consumption and both IFG and T2DM, but no clear patterns were observed. CONCLUSION: The study found that with very few exceptions, associations between traditional risk factors examined and both IFG and T2DM did not vary by age or sex among the West African population. Policies and public health intervention strategies for the prevention of T2DM and IFG should target adults of any age or sex in West Africa.

Associations between obesity indices and both type 2 diabetes and impaired fasting glucose among West African adults: Results from WHO STEPS surveys.

BACKGROUND AND AIM: Various obesity indices such as BMI, waist circumference (WC), waist-hip ratio, (WHR) and waist-to-height ratio (WHtR) are associated with the risk of type 2 Diabetes Mellitus (T2DM). Given few studies examining the strength of the association in this population, we aimed to identify which obesity indices are most strongly associated with T2DM and impaired fasting glucose (IFG) among adults from five West African countries. METHODS AND RESULTS: Data from 15,520 participants from the World Health Organisation (WHO) STEPs surveys in Burkina Faso, Benin, Mali, Liberia, and Ghana were included in analyses. Multinomial logistic regression was used to calculate the relative risk (RR) per standard deviation (SD) of each anthropometric measure, modelled as both continuous variables and as categorical variables based on established cut-points. In the analyses with continuous variables, the unadjusted RRs for T2DM per SD were 1.30 (1.23, 1.37) for body mass index (BMI); 1.56 (1.46, 1.67) for WC; 2.57 (2.15, 3.09) for WHtR and 1.16 (1.03, 1.31) for WHR. WHtR showed the strongest association with T2DM in all adjusted analyses. For models using categorical variables based on established cut-points, obesity defined using waist circumference (OB-WC) and OB-BMI showed the strongest associations with T2DM, and OB-WHR, the weakest association in all adjusted analyses. CONCLUSION: WHtR and WC appear to be the indices most strongly associated with T2DM and IFG respectively. Given its simplicity, WC may be the metric that most usefully conveys risk for T2DM in West African adults.