Are body mass or insulin resistance independently associated with cardiovascular risk factors in non-diabetic elderly Nigerians?

Abstract

The aim was to establish whether risk factors for cardiovascular disease (CVD) are positively and independently associated with fasting insulin and/or body mass and waist-hip ratio in healthy elderly Nigerian subjects. Fasting plasma glucose, insulin, total cholesterol, triglycerides, blood pressure, and basal insulin resistance (HOMA method) were measured in 500 healthy elderly (> or = 55 years) Nigerian volunteers (295 men, 205 women). Associations between blood pressure, triglycerides or cholesterol and fasting insulin, HOMA, body mass index (BMI) or waist-hip ratio were examined using linear regression. Age was controlled for in all analyses. In men, diastolic and systolic blood pressure were strongly associated with BMI, while there was no evidence of an independent relationship with fasting insulin or HOMA. Triglycerides were strongly associated with waist-hip ratio, with a weaker independent association with HOMA but not fasting insulin; fasting insulin and HOMA showed strong independent associations with total cholesterol. In women diastolic and systolic blood pressure were also strongly associated with BMI, but there was an independent relationship with fasting insulin for diastolic blood pressure and a less significant (p = 0.057) one for systolic blood pressure. Triglycerides were significantly associated with BMI but none of the other variables; there were no significant associations with cholesterol. There was no evidence of interaction between fasting insulin or HOMA and BMI or waist-hip ratio. The results suggest the hypotheses that in this population BMI or waist-hip ratio are stronger determinants of blood pressure and triglyceride levels than fasting insulin or HOMA, and that where insulin does play a role its effects are separate and additive.