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 diabetes among mothers of probands with type 2 diabetes than among fathers. This analysis is vulnerable to biases, and this pattern has not been observed in all populations or races.


METHODS
We assessed evidence for excess maternal transmission 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 provided. Accuracy of family information reported by probands was also evaluated 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 greater 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 races and both sexes; however, the effect size was clinically insignificant in African-Americans and male offspring. In general, probands provided more complete 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 generally > 0.70).


CONCLUSIONS
Excess maternal transmission was observed in all races and both sexes, although the size of the excess was negligible in African-Americans and male offspring. Potential reporting and censoring biases are discussed.
Karter
A J
AJ
Division of Research, Kaiser Permanente, Oakland, California 94611-5714, USA. ajk@dor.kaiser.org
Rowell
S E
SE
Ackerson
L M
LM
Mitchell
B D
BD
Ferrara
A
A
Selby
J V
JV
Newman
B
B
D000293:Adolescent; D000328:Adult; D000368:Aged; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology* / Q000235:genetics*; D005220:Fathers; D005260:Female; D018392:Genomic Imprinting; D006801:Humans; D008297:Male; D008875:Middle Aged; D009035:Mothers; D009679:Nuclear Family; D015995:Prevalence; D044469:Racial Groups; D012042:Registries; D015203:Reproducibility of Results; D012727:Sex Characteristics