The impact of hyperglycemia on urinary albumin excretion in recent onset diabetes mellitus type II

BACKGROUND: Increased urinary albumin excretion (UAE) in diabetes is a sensitive marker of microvascular injury and a reliable predictor of cardiovascular outcomes. Hypertension-induced hemodynamic pressure load, diabetes-related metabolic processes and large artery stiffening have all been implicated in the development of microalbuminuria. We investigated whether hyperglycemia per se, or rather increased blood pressure (BP) and macrovascular dysfunction, is a stronger predictor of UAE at the earliest stages of diabetes. METHODS: Consecutive newly diagnosed patients with diabetes type 2, who were normoglycemic within a year’s time prior to diagnosis, were enrolled. UAE was estimated in 24-h urine samples. Both office and 24-h ambulatory BP was recorded. Arterial stiffness was evaluated by measurement of carotid-femoral pulse wave velocity (PWV) with applanation tonometry. RESULTS: Among 71 newly diagnosed patients with median diabetes duration of just 1 month, 15.5% presented microalbuminuria. UAE did not differ between hypertensive and normotensive diabetics; however, newly diagnosed patients for both hypertension and diabetes exhibited significantly higher levels of UAE, compared to diabetic patients with long-standing hypertension. UAE strongly and significantly correlated with office systolic BP, HbA1c, PWV and estimated glomerular filtration rate. However, in the multivariate analysis adjusting for these factors, only HbA1c was independently associated with UAE (beta = 0.278, p = 0.049). CONCLUSIONS: Hyperglycemic state emerges as a powerful predictor of increased UAE even at the earliest stages of diabetes. The relative contribution of hypertension and macrovascular dysfunction to the development of microalbuminuria seems to be obscured by hyperglycemia, even in patients whose diabetes onset does not exceed a few months’ time.