Elsevier

Kidney International

Volume 58, Issue 1, July 2000, Pages 302-311
Kidney International

Original Article
Higher incidence of diabetic nephropathy in type 2 than in type 1 diabetes in early-onset diabetes in Japan

https://doi.org/10.1046/j.1523-1755.2000.00166.xGet rights and content
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Higher incidence of diabetic nephropathy in type 2 than in type 1 diabetes in early-onset diabetes in Japan.

Background

Whether the type of diabetes, race, and year and age of diagnosis affect the incidence of diabetic vascular complications is unknown. That both type 1 and type 2 diabetes occur in the young Japanese population prompted us to investigate whether the type of diabetes and the year of diagnosis are related to the incidence of nephropathy.

Methods

Of the 17,256 diabetic patients who visited the outpatient clinic at our diabetes center between 1965 and 1990, 1578 (9.1%) had early-onset diabetes (diagnosed before the age of 30); of these, 620 (39%) had type 1, and 958 (61%) had type 2 diabetes. The incidence of nephropathy was analyzed in the patients according to postpubertal duration and year of diagnosis.

Results

The cumulative incidence of nephropathy after 30 years of postpubertal diabetes was significantly higher (P < 0.0001) in type 2 diabetic patients (44.4%, 95% CI, 37.0 to 51.8%) than in type 1 diabetic patients (20.2%, 95% CI, 14.9 to 25.8%). The incidence of nephropathy among type 1 diabetic patients has declined during the past two decades, whereas it has not among type 2 diabetic patients. The rate ratio for type 2 diabetic patients diagnosed between 1980 and 1984 relative to type 1 diabetic patients diagnosed in the same period was 2.74 (95% CI, 1.17 to 6.41).

Conclusions

The incidence of nephropathy has declined in Japanese patients with type 1 but not in those with type 2 diabetes. In young Japanese patients, because of the higher incidence of nephropathy in type 2 diabetes and the higher prevalence of type 2 than type 1 diabetes, type 2 diabetes is likely the major cause of diabetic nephropathy.

Keywords

insulin-dependent diabetes
noninsulin-dependent diabetes
childhood diabetes
end-stage renal failure
proteinuria
retinopathy

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