Clinical features and health-care costs of diabetic nephropathy

The nephropathy complicating insulin-dependent diabetes mellitus (IDDM) has been well studied, but that complicating non-insulin-dependent diabetes mellitus (NIDDM) is less well defined. In patients with IDDM, the glomerular filtration rate is often increased early in the course of the disease, approaches normal with insulin therapy, but tends to remain slightly elevated throughout the ensuing 10-15 yr of insulin dependency. After the onset of overt azotemia, end-stage renal disease (ESRD) develops in approximately 5 yrs. Proteinuria may be intermittently positive in the earliest stages of diabetes, evolving into intermittent and then persistent microalbuminuria, which in turn blossoms into macroalbuminuria. Because 40-50% of IDDM patients develop proteinuria and two-thirds of this subpopulation develop ESRD, some 20-30% of any given cohort of IDDM patients eventually need dialysis or transplantation. Evidence indicates that diabetic nephropathy is associated with a greater incidence of eye, nerve, heart, and peripheral vascular disease. Nondiabetic renal disease complicating IDDM and NIDDM is associated with a lesser frequency and severity of these extrarenal manifestations. The prevalence of retinopathy increases with advancing nephropathy. Roughly two-thirds of the deaths from IDDM are related to renal failure, and most of the remainder are caused by associated cardiovascular disease. Transplantation from living relatives carries the best prognosis for survival, and little difference is seen between hemodialysis, peritoneal dialysis, and cadaver transplantation. The health-care costs of treating diabetic nephropathy are also reviewed.