Differential management and associations of dyslipidaemia and hypertension by glycaemic status in urban South Africans

Abstract

Background. Dyslipidaemia and hypertension care have not been reported in large samples of community-based participants with known diabetes (KD) nor compared with individuals at high risk for diabetes.Objectives. To describe the management and associations of dyslipidaemia and hypertension in adults with KD, newly diagnosed diabetes (NDD) and normoglycaemia. Methods. This urban population-based cross-sectional study comprised participants with KD, NDD and normoglycaemia. Participants at high risk for diabetes but without KD underwent oral glucose tolerance tests; those who were subsequently classified as NDD or normoglycaemic were included in this study. Data collection comprised administered questionnaires, clinical measurements and biochemical analyses. Multivariable logistic regressions determined the associations with hypertension and dyslipidaemia management in separate models. Results. Among 618 participants (82% women), aged median 58 years, there were 339 participants with KD, 70 with NDD and 209 with normoglycaemia. Prevalence of hypertension (BP ≥140/90 mmHg or on treatment) and dyslipidaemia (raised low-density lipoprotein cholesterol >3 mmol/L or on treatment) was highest in KD (89% and 83%) compared with NDD (64% and 74%) and normoglycaemia (66% for both) (p<0.001). Detected or known hypertension was highest in KD (97.4%), followed by NDD (88.9%) and normoglycaemia (80.3%). Among participants with known or detected hypertension, those with KD were most likely to be treated (90.2%) compared with NDD (77.5%) and normoglycaemia (74.5.%). Hypertension control among participants on treatment was highest in KD (69.5%) compared with NDD (51.6%) and normoglycaemia (61.0%). Participants with KD had significantly higher rates of previously detected dyslipidaemia (85.1%) compared with NDD (36.5%) and normoglycaemia (35.5%). KD participants were also more likely to be treated for their previously detected dyslipidaemia (85.4%) and to be controlled when on treatment (56.3%) compared with their counterparts (NDD: 63.2% and 33.3%, normoglycaemia: 61.2% and 43.3%, respectively). Diabetes control was poor; only 20% of those with KD had HbA1c <7%. In the regression models, compared with normoglycaemia, KD was associated with hypertension detection (odds ratio (OR) 6.91, 95% confidence interval (CI) 2.25 - 21.22) and control (OR 2.05, 95% CI 1.04 - 4.02). KD compared with normoglycaemia was associated with dyslipidaemia detection (OR 10.29, 95% CI 5.21 - 20.32) and treatment (OR 3.94, 95% CI 1.68 - 9.27). Sociodemographic and cardiovascular disease risk factors were generally not associated with hypertension or dyslipidaemia management. Conclusion. Albeit that diabetes control was poor and required better management, dyslipidaemia and hypertension prevalence were higher and better managed in KD than NDD and normoglycaemia. Different approaches are required to improve glucose control in KD, better identify NDD and monitor and prevent diabetes in high-risk individuals. Also important would be to improve care of hypertension and dyslipidaemia in those without KD.