Role of Glycemic Control and Blood Pressure in the Development and Progression of Nephropathy in Elderly Japanese NIDDM Patients

Abstract

OBJECTIVE To investigate the role of glycemic control and blood pressure in the development and progression of nephropathy and to suggest goals for glycemic control and blood pressure for the prevention of nephropathy in elderly Japanese NIDDM patients. RESEARCH DESIGN AND METHODS A total of 123 age- and diabetes duration-matched elderly Japanese NIDDM patients (aged 60−75 years; 74 normoalbuminuric and 49 microalbuminuric) were retrospectively studied for 6 years. RESULTS The group that developed microalbuminuria from normoalbuminuria (group NM: n = 24) showed a higher 6-year mean HbA1c than the group that remained normoalbuminuric (group NN: n = 50; 9.0 ± 0.8 vs. 8.1 ± 0.8%, P < 0.01) in spite of no significant difference in 6-year mean blood pressure (MBP). On the other hand, the group that progressed from microalbuminuria to overt proteinuria (group MP: n = 26) showed a higher 6-year MBP than the group that remained microalbuminuric (group MM: n = 23; 106 ± 5 vs. 95 ± 6 mmHg, P < 0.01) in spite of no significant difference in 6-year mean HbA1c. The cutoff level of HbA1c separating group NN from group NM was 8.5% (normal range ≤ 6.5%), and that of MBP separating group MM from group MP was 100 mmHg. CONCLUSIONS Glycemic control is a more potent factor than blood pressure level on the development of microalbuminuria. However, as far as the progression of microalbuminuria to overt proteinuria is concerned, hypertension is the most crucial factor in elderly NIDDM patients. Suggested goals for glycemic control and blood pressure level for the prevention of nephropathy in elderly Japanese patients are an HbA1c of ≤8.5% (equivalent to 7.8% in the current measurement of stable HbA1c; normal range ≤5.8%) and an MBP of ≤ 100 mmHg.