Effect of intensive glycemic control on microalbuminuria in type 2 diabetes

OBJECTIVE - Microalbuminuria can reflect the progress of microvascular complications and may be predictive of macrovascular disease in type 2 diabetes. The effect of intensive glycemic control on microalbuminuria in patients in the U.S. who have had type 2 diabetes for several years has not previously been evaluated. RESEARCH DESIGN AND METHODS - We randomly assigned 153 male patients to either intensive treatment (INT) (goal HbA(1c) 7.1%) or to standard treatment (ST) (goal HbA(1c) 9.1%; P = 0.001), and data were obtained during a 2-year period. Mean duration of known diabetes was 8 years, mean age of the patients was 60 years, and patients were well matched at baseline. We obtained 3-h urine samples for each patient at baseline and annually and defined microalbuminuria as an albumin:creatinine ratio of 0.03-0.30. All patients were treated with insulin and received instructions regarding diet and exercise. Hypertension and dyslipidemia were treated with similar goals in each group. RESULTS - A total of 38% of patients had microalbuminuria at entry and were evenly assigned to both treatment groups. INT retarded the progression of microalbuminuria during the 2-year period the changes in albumin:creatinine ratio from baseline to 2 years of INT versus ST were 0.045 vs. 0.141, respectively (P = 0.046). Retardation of progressive urinary albumin excretion was most pronounced in those patients who entered the study with microalbuminuria and were randomized to INT. Patients entering with microalbuminuria had a deterioration in creatinine clearance at 2 years regardless of the intensity of glycemic control. In the group entering without microalbuminuria, the subgroup receiving ST had a lower percentage of patients with a macrovascular event (17%) than the subgroup receiving INT (36%) (P = 0.03). Use of ACE inhibitors or calcium-channel blockers was similarly distributed among the groups. CONCLUSIONS - Intensive glycemic control retards microalbuminuria in patients who have had type 2 diabetes for several years but may not lessen the progressive deterioration of glomerular function. Increases in macrovascular event rates in the subgroup entering without albuminuria who received INT remain unexplained but could reflect early worsening, as observed with microvascular disease in the Diabetes Control and Complications Trial.