Most survey-based prevalence estimates of type 1 diabetes among adults have been based on self-reported information about a young age at diagnosis (e.g., <30 years and <40 years) and insulin use within a year of diagnosis.
However, this estimation approach misses type 1 diabetes in adults
with older age of onset and may misclassify some cases of type 2 diabetes as type 1 if insulin use begins soon after diagnosis.
The major goal of this project is to evaluate the validity of survey questions (or algorithms based on them) to distinguish between adults (aged ≥18 years of age) with type 1 and type 2 diabetes in a representative sample of adult diabetic patients in a diabetes patient registry or database.
Using a gold standard, validity will be assessed by examining the sensitivity, specificity, and positive predictive value of algorithms to identify type of diabetes across demographic strata such as age, sex, and race.
A secondary goal is to validate definitions of type of diabetes using electronic health records.