HIGH-INCIDENCE OF DIABETIC NEPHROPATHY IN EARLY-ONSET JAPANESE NIDDM PATIENTS - RISK ANALYSIS

OBJECTIVE-Because early-onset Japanese NIDDM patients (diagnosed befor e age 30 years) can develop diabetic end-stage renal failure (ESRF) in their thirties, this study was performed to elucidate the incidence a nd determinants for the development of diabetic nephropathy. RESEARCH DESIGN AND METHODS-The incidence of diabetic nephropathy and its relat ionship to baseline characteristics and long-term metabolic control we re determined in 426 early-onset Japanese NIDDM patients who were foll owed for a mean of 6.8 years. RESULTS-Of these 426 patients, 41 develo ped diabetic nephropathy manifested by persistent proteinuria (inciden ce rate [95% CI]/1,000 person-years; 14.1 [10.4-19.1]). Among patients whose mean HbA(1c) (measured by a high-performance chromatography met hod that is standardized and comparable to the one used in the Diabete s Control and Complications Trial study) was around 7% or less, few de veloped nephropathy. The incidence of nephropathy increased with incre asing mean HbA(1c) level in a dose-dependent manner (X-2 trend = 49.9, P < 0.0001). Diastolic blood pressure and duration of diabetes at ent ry had significant predictive effects independent of metabolic control . CONCLUSIONS-The incidence rate of diabetic nephropathy in early-onse t Japanese NIDDM patients is potentially high, similar to or higher th an that in Pima Indian NIDDM or Caucasian IDDM patients of comparable age. Diabetic nephropathy in NIDDM patients aged in their thirties or forties is likely to be an early feature that leads to ESRF; and this would contribute to the marked increase in the number of new patients with diabetic ESRF in Japan. NIDDM is a serious disease if near-normal glycemia is not achieved.