Type 1 diabetics who have a sibling with diabetic kidney disease have twice the risk of also developing this complication, according to a new report.

The finding, which appears in the journal Diabetes, is based on an analysis of data from 537 Finnish families in which two or more siblings had type 1 diabetes. A total of 537 patients diagnosed with diabetes between 1965 and 1979, and their 616 diabetic siblings, were followed through 2001 for the development of diabetic kidney disease.

A total of 323 cases of diabetic kidney disease occurred in the study group, lead author Dr. Valma Harjutsalo, from the National Public Health Institute in Helsinki, and colleagues note.

The rates of diabetic kidney disease among siblings of affected and unaffected type I diabetes were 38 percent and 17 percent, respectively, a statistically significant difference.

Subjects with a sibling with kidney disease were 2.3 times more likely to develop the condition themselves compared with subjects without a sibling with diabetic kidney disease. The risk was even higher if severe kidney disease was present.

Other risk factors for diabetic kidney disease included male gender, being diagnosed with diabetes during puberty, and having a parent with type 2 diabetes.

This is the first long-term, population-based study of diabetic kidney disease among siblings of type 1 diabetic patients, the authors note.

Although most diabetic sibling pairs don’t both have kidney disease, having an affected sibling doubles a person’s risk, they add.

SOURCE: Diabetes, September 2004.