Effect of glycemic control on microalbuminuria and arterial blood pressure in patients with type 1 diabetes

Background: Diabetic nephropathy is the leading cause of hypertension in type 1 diabetes. Microalbuminuria is usually the first manifestation of renal disease and antedate hypertension. The aim of this study was to investigate relationships between glycemic control, hypertension and microalbuminuria in type 1 diabetics.

Methods: We studied 27 type 1 diabetics, 18 male and 9 female, aged 18-50 years, with a duration of diabetes <20 years. Glycemic control was assessed using glycosylated hemoglobin (HbA1c) measurements, fructosamine and lipid analysis. 24-h urinary albumin excretion rate was evaluated by radioimmunoassay. Patients with persistent urinary albumin excretion rate 30-300 mg/24 h were defined as microalbuminuric (Group A--41% patients) and lower than that, as normoalbuminuric (Group B--59%). We examined them twice: first in poor glycemic control and then in good glycemic control.

Results: We found significant differences (Student's t-test) between groups in regard to microalbuminuria (p <0.01), diabetes duration (p=0.05), systolic blood pressure (BP) and diastolic BP (p<0.05). Systolic BP (p<0.01), diastolic BP (p<0.01) and microalbuminuria (p=0.05) positively correlated (Spearman's rho) with poor glycemic control in Group A. In both groups there was a significant improvement in glycemic control and regression in systolic and diastolic BP (p<0.01), but only Group B showed significant reduction in urinary albumnin excretion rate (p<0.01).

Conclusions: In this study, type 1 diabetics showed regression in systolic and diastolic hypertension with improvements of glycemic control regardless of presence of microalbuminuria, but only normoalbuminuric showed significant reduction in urinary albumin excretion rate.