Accuracy of Reported Family History of Diabetes Mellitus: Results From San Luis Valley Diabetes Study

There are two possible sources of bias in the assessment of family history of diabetes: 1) a person with diabetes may be more likely to report a diabetic relative than a nondiabetic person would be, and 2) relatives of individuals with diabetes may be more likely to be tested for diabetes than relatives of nondiabetic individuals. We conducted a study on a subsample of families of subjects in the San Luis Valley Diabetes Study to examine these issues. A sample of 5 White and 5 Hispanic subjects (probands) with diabetic glucose tolerance tests and the same number with normal glucose tolerance were selected. The 20 probands all provided contact information on their 227 primary family members. Ninety-two percent of the family members had interviews completed by themselves or, if deceased, by surrogates other than the proband. Family members were asked by telephone if they had ever been tested for diabetes, when they had been most recently tested, why they had been tested, and if they had ever been told they had diabetes. The results showed that study subjects accurately reported family history of diabetes, because there were no discrepancies between proband and family reports. A positive family history of diabetes was associated with increased reported screening in Hispanics, but a similar effect in White families was not seen. Women were also more likely to report being screened than men regardless of whether there was a positive family history of diabetes. These data indicate that, although diabetic and control subjects accurately report their family history of known diabetes, indications of differential screening exist that may alter the amount of known and subsequently reported diabetes in families.