Excess maternal transmission of type 2 diabetes - The northern California Kaiser Permanente diabetes registry

OBJECTIVE - To assess excess maternal transmission of type 2 diabetes in a multiethnic cohort. Previous studies have reported higher prevalence of dia betes among mothers of probands with type 2 diabetes than among fathers. Th is analysis is vulnerable to biases, and this pattern has not been observed in all populations or races. RESEARCH DESIGN AND METHODS - We assessed evidence for excess maternal tran smission among 42,533 survey respondents with type 2 diabetes (probands) by calculating the prevalence of diabetes in their siblings and offspring. To assess data quality, we evaluated completeness of family history data prov ided. Accuracy of family information reported by probands was also evaluate d by comparing survey responses in a subsample of 206 probands with family histories modified after further interviews with relatives. RESULTS - Siblings (n = 60,532) of probands with affected mothers had a gre ater prevalence of diabetes (20%) than those with affected fathers (17%) (P < 0.001 for adjusted odds ratios). Prevalence of diabetes was higher among the offspring (n = 72,087) of female (3.4%) versus male (2.2%) probands (P < 0.001 for adjusted odds ratios). These patterns were evident in all race s and both sexes; however, the effect size was clinically insignificant in African-Americans and male offspring. In general, probands provided more co mplete data about diabetes status for the maternal arm of the pedigree than the paternal arm. Completeness of knowledge was not related to proband sex , but was related to education and race, and inversely to age. Accuracy of proband-reported family history was consistently good (kappa statistics gen erally >0.70). CONCLUSIONS - Excess maternal transmission was observed in all races and bo th sexes, although the size of the excess was negligible in African-America ns and male offspring. Potential reporting and censoring biases are discuss ed.