Comparison of the course to end-stage renal disease of Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetic nephropathy

Is the course leading to diabetic end-stage renal disease similar for Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes mellitus? We identified all diabetic end-stage renal disease patients starting renal replacement therapy from 1989 to 1991 in two urban counties in Texas. Three ethnic/racial groups were enrolled: Mexican Americans, non-Hispanic Whites, African Americans. Patients were interviewed and their medical records, both inpatient and out-patient, were abstracted for relevant diagnostic and therapeutic information. We attempted to obtain records as far back as the onset of diabetes or hypertension and from all physicians who had cared for the patient. An historical algorithm was used to determine diabetic type. Of the patients enrolled, 91 were Type 1 and 438 were Type 2 diabetic patients. Type 1 diabetic patients had higher mean glucose levels in the first 10 years of diabetes (16.3 vs 11.4 mmol/l) but lower systolic blood pressures (148 vs 157 mmHg). The duration of diabetes prior to end-stage renal disease was longer for Type 1 than Type 2 patients (22 vs 17 years). Type 1 diabetic patients were more likely to have other microvascular complications (retinopathy, neuropathy, gastroparesis), less likely to have coronary disease (myocardial infarction and congestive heart failure), and had similar rates of stroke and vascular surgery procedures (carotid endarterectomy, coronary artery bypass surgery, aortofemoral bypass). Type 1 and Type 2 diabetic patients were just as likely to have a first degree relative with hypertension (60.5 vs 65.5%). The late manifestations of end-stage renal disease were similar between the two groups (kidney size, proteinuria, slope of the inverse of creatinine, laboratory data prior to end-stage renal disease, reasons for starting dialysis). The course to end-stage renal disease may be different for Type 1 and Type 2 diabetes, with hyperglycaemia playing a more dominant role in Type 1 and hypertension playing a more dominant role for Type 2. The Type 1/Type 2 differences in patterns of other diabetic complications add weight to this hypothesis. However, the late course of the renal disease and the end result on the kidney is very similar.