oa Journal of Endocrinology, Metabolism and Diabetes in South Africa - Unsuspected glucose abnormalities in patients with coronary artery disease
<I>Objectives.</I> To compare the ability of fasting glucose, glycosylated haemoglobin (HbA<sub>1c</sub>), the American Diabetic Association (ADA) score and measures of the metabolic syndrome (waist circumference, high-density lipoprotein (HDL), and triglycerides) in predicting an initial diagnosis of diabetes mellitus or abnormal glucose tolerance based on the World Health Organization (WHO) criteria. <br><I>Design.</I> A cross-sectional, diagnostic study was undertaken of 120 patients admitted to the cardiology wards of Pretoria Academic Hospital for elective coronary angiographic studies. <br><I>Main outcome measures.</I> All subjects underwent a modified glucose tolerance test whereby fasting and 2-hour post glucose (75 g) plasma glucose levels were measured. Using the revised WHO criteria, the overall incidence of diabetes was found to be 11.7% (95% confidence interval (CI): 6.5 - 19) and the overall incidence of abnormal glucose tolerance was 46% (CI: 37 - 55). <br><I>Results.</I> In univariate analysis for the diagnosis of diabetes, HbA<sub>1c</sub> (p < 0.05) yielded the largest area (0.76) under the receiver operating characteristic (ROC) curve, with a sensitivity of 21%, specificity of 99%, positive predictive value (PPV) of 75% and negative predictive value (NPV) of 91%. For the prediction of abnormal glucose tolerance, applying multivariate analysis using a logistic regression model, the combination of age, ethnic group, serum HDL, serum triglycerides and HbA<sub>1c</sub> yielded an area under the ROC curve of 0.79, sensitivity of 66%, specificity of 80%, PPV of 76% and a NPV of 71%. <br><I>Conclusion.</I> Most subjects with diabetes mellitus (9 of 14) would not have been detected if a 2-hour oral glucose tolerance test had not been done. Addition of either HbA<sub>1c</sub> or lipid parameters to the model of age and ethnic group were similar in predicting abnormal glucose tolerance.
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