Blood glucose control and albuminuria in type 1 diabetes mellitus

The relationship between long-term blood glucose control and albuminuria in type 1 diabetes was investigated in 42 male and 58 female patients who had had diabetes mellitus for more than 7 years. Their mean (+/- SD) age and diabetes duration were 18.6 +/- 3.6 and 12.1 +/- 3.5 years, respectively. For periods of observation ranging from 1 to 6 years (mean 4.4 +/- 1.5), hemoglobin A1c (HbA1c) was measured two to six times yearly (mean of 8.8 +/- 3.9 determinations per patient). Albumin excretion rate (AER) was measured in single-void urine samples two to four times in 93 patients and once in the other seven patients. The 52 patients with mean HbA1c no more than 9.0% had significantly lower mean AER than those whose HbA1c was greater than 9.0% (20.1 +/- 24.6 vs 265 +/- 1005 mg/gm Cr, p less than 0.001). Only five (9.6%) of these 52 patients had elevated AER values (greater than 40 mg/gm Cr), whereas 21 (43.7%) of 48 patients whose mean HbA1c was greater than 9.0% had elevated AER values (p less than 0.001). Six male but no female patients had mean AER values greater than 300 mg/gm Cr. The 74 patients with normal AER had significantly lower mean HbA1c values than the 26 with elevated AER (8.6 +/- 1.5 vs 10.1 +/- 1.6%, p less than 0.001). These results support the contention that maintenance of HbA1c levels at no more than 9% (one and one-half times the upper limit of normal) will significantly decrease the likelihood that diabetic nephropathy will develop.