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- Afflicts 35–40% of type 1 and type 2 diabetics with an increasing incidence associated with type 2 diabetes mellitus.
- An initial period of glomerular hyperfiltration.
- Progressively increasing proteinuria.
- A gradual decline in the glomerular filtration rate (GFR).
- Results in renal failure.
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Diabetic nephropathy is a serious public health concern because it has become the leading cause of end-stage renal disease (ESRD) in most developed countries and is associated with increased cardiovascular mortality. Tracking both the incidence and prevalence of ESRD attributed to diabetes underscores its annual growth rate over the past decade in excess of 9%. According to the 2004 report of the U.S. Renal Data System (USRDS), in 2002, of 419,263 patients in the United States receiving either dialytic therapy or a kidney transplant, 149,614 had diabetes, a prevalence rate of 35.6%. The incidence rate was 44.5% in 2002, with 42,665 of 149,614 new (incident) cases of ESRD attributed to diabetes (Figure 54–1). This increase is mainly attributed to an increase in the occurrence of diabetes, especially type 2 diabetes; the extended life span of diabetic patients due to improved management of comorbid conditions; and the acceptance of patients for replacement therapy who in the past were excluded.
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Diabetic nephropathy is characterized by an initial period of glomerular hyperfiltration associated with progressively increasing proteinuria, followed by a gradual decline in the GFR, eventually resulting in renal failure. Diabetic nephropathy afflicts 35–40% of type 1 and type 2 diabetic patients. While the natural history of diabetic nephropathy is well studied in type 1 diabetic patients, recent studies have shown a similar course of diabetic nephropathy in type 2 diabetic patients as well. In the past 2 decades, much has been learned about the possible pathogenesis of diabetic nephropathy leading to the development and use of specific therapies that have been effective in slowing progression to renal failure.
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A cumulative incidence of diabetic nephropathy has been documented after 20–25 years of diabetes in both type 1 and type 2 individuals. Recent studies demonstrated that present treatment strategies substantially reduce the progression and incidence of diabetic nephropathy in type 1 diabetes. For example, a study from Sweden showed a substantial decline in albuminuria after 25 years of diabetes from 30% in patients in whom diabetes developed from 1961 to 1965 to 8.5% in those with onset from 1966 to 1970 and 13% in those diagnosed from 1971 to 1975. Similarly, the Steno Diabetes Center reported that in the same cohorts, the cumulative incidence of diabetic nephropathy after 20 years fell from 31.3% to 13.7%. Improved glycemic control, better control of blood pressure, and reduced prevalence of smoking were associated with the lower incidence of nephropathy.
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In contrast to the decreasing incidence of diabetic nephropathy in type 1 diabetes, ...