Diabetic Nephrepathy

 John Wang, M.D.

(Presented at the CAMS 2000 Semiannual Scientific Meeting)

Diabetic nephropathy is the most common cause of end-stage renal disease (ESRD) in the United States.  It accounts for 1/3 of all patients in the US ESRD Program and costs Medicare more that $2 billion annually.   More strikingly, morbidity and  mortality are very high for the individual who develops diabetic nephropathy.  In general, its prognosis is worse than patients with neoplastic disease.

            Diabetic nephropathy, as manifested by proteinuria, rarely develops before 10 years’ duration of diabetes.  Approximately 40% of type 1 patients have proteinuria after 40 years.  The incidence peaks at 15-17 years’ duration of diabetes.   Risk factors for the development of diabetic nephropathy are hypertension, poor glycemic control, family history, hyperlipidemia and cigarette smoking.  In the United States, minorities (African, Mexican, and Native-Americans) with diabetes have much higher rates compared to Caucasians.

            Early diabetic nephropathy is manifested by the development of microalbuminuria.  hyperfiltration, hyper-tension, and poor blood sugar control.  The current recommendation is to test patients with type 1diabetes of 5 years or more for microalbuminuria on a yearly basis.  Type 2 diabetes should be tested at the time of diagnosis and yearly thereafter.

            Major therapeutic interventions for patients with diabetic nephropathy include antihypertensive therapy, improved diabetes control, restriction of dietary protein intake, treatment with inhibitors for the formation of advanced glycosylation end-products (AGEs), and a variety of others.  Current JNC IV recommendation is that blood pressure should  be reduced to below 130/85 mmHg.  Angiotensin converting enzyme inhibitors, calcium channel blockers, alpha-blockers, and diuretics in low doses are preferred.  If ACE inhibitor is not tolerated, Angiotensin II receptor blockers may be substituted.  Calcium channel blockers offer some degree of renal protection.  It has been suggested that a combination of ACE inhibitors and calcium channel blockers may be of more benefit.

            As renal function declines, uremia ensues.  Once patients reach ESRD, their options are renal replacement therapies, i.e. dialysis or kidney transplantation.  #

(Dr. Wang is Associate Professor of Medicine at Weill Medical College of Cornell University