Metabolic syndrome, undiagnosed diabetes mellitus and insulin resistance are highly prevalent in urbanised South African blacks with coronary artery disease.

BACKGROUND

The prevalence of coronary artery disease (CAD) is low in South African blacks, despite increasing westernisation and the accompanying rise in risk factors that are common to CAD and the metabolic syndrome (MS).

AIM

To assess the prevalence of the MS and abnormal glucose regulation in black patients with established CAD, who had no previously known diabetes mellitus (DM).

METHODS

In 40 patients, anthropometric and biochemical variables were measured by standard methods. MS risk factors were analysed according to the National Cholesterol Education Program Adult Treatment Panel III guidelines. Glucose regulation was assessed by the oral glucose tolerance test, and insulin resistance was evaluated using the hyperinsulinaemic euglycaemic clamp technique (M-value).

RESULTS

MS was present in 24 patients (60%) and absent in 16 patients (40%). Abdominal obesity, measured as increased waist circumference (WC), was the risk factor that differentiated the two groups and, together with hypertension and elevated glucose, formed the most frequent risk-factor combination. No significant differences were found in the proportions of males or females above and below the various cut-off points for gender-associated risk factors (WC and HDL cholesterol). There was a significant correlation between WC and M-value (r = -0.3595; p = 0.02). Half the patients had abnormal glucose regulation, comprising impaired glucose tolerance (IGT) in 30% and DM in 20% of the patient cohort.

CONCLUSIONS

MS was highly prevalent in our black patients with CAD. Increased WC was the most important risk factor and, together with hypertension and elevated glucose, formed the most frequent risk-factor combination. Abdominal obesity was significantly related to insulin resistance. Previously undiagnosed impaired glucose tolerance (IGT) and DM were common abnormalities.