MICROALBUMINURIA IN TYPE-2 DIABETES - AN INDEPENDENT PREDICTOR OF CARDIOVASCULAR MORTALITY

Background: Microalbuminuria has been shown to be associated with card iovascular mortality in type 2 diabetic subjects. It is unclear to wha t extent this is due to the increased prevalence of other cardiac risk factors. Aims: To examine the relationship of urine albumin excretion to cardiovascular mortality and to determine its status as an indepen dent risk factor. Methods: In a prospective longitudinal study from 19 86-1993 we followed 666 type 2 diabetic subjects from a diabetes outpa tient service. Cardiovascular risk factors including urine albumin con centration were measured at study entry. Cox proportional hazards regr ession was used to determine risk factors for mortality. The hazard ra tios of microalbuminuria and macroalbuminuria for all cause, cardiovas cular and coronary heart disease mortality were determined after accou nting for other cardiac risk factors including blood pressure, glycate d haemoglobin, total cholesterol, HDL cholesterol, triglycerides, urea , smoking, body mass index, patient age and disease duration. Results: The prevalence of urine albumin of 30-300 mg/L at study entry was 31. 7%. A total of 167 deaths occurred (80 from cardiovascular disease). M ortality hazard ratios in subjects with urine albumin of 30-300 mg/L a s compared to <30 mg/L, adjusted for age, sex and other cardiovascular risk factors were 1.77 (95% CI 1.22-2.57, p=0.002) for all causes, 2. 34 (95% CI 1.38-3.99, p=0.002) for cardiovascular and 1.78 (95% CI 0.9 7-3.26, p=0.061) for coronary heart disease (CHD) mortality. Other fac tors significantly associated with cardiovascular mortality included d iastolic blood pressure, HDL cholesterol and glycated haemoglobin. Tot al cholesterol and log triglyceride were significantly associated with CHD mortality. Disease duration, age at diagnosis, smoking and body m ass index were not related to cardiovascular or CHD mortality. Conclus ions: We confirm microalbuminuria as an independent predictor of morta lity in type 2 diabetes despite its association with a number of conve ntional cardiovascular risk factors.