1677-P: Ethnic Differences in the Peri-diagnostic Period of Type 1 Diabetes (T1D)

We have previously shown that Hispanic ethnicity influences progression to T1D with interaction by obesity in children < 12 years of age. In this study, we aimed to compare ethnicities for characteristics in the peri-diagnostic period of T1D. We studied participants in TrialNet New Onset Intervention Trials (n=501, 9.4% Hispanics, 86.4% non-Hispanic whites [NHW], 4.2% non-Hispanic other) followed prospectively. We analyzed clinical, immunological and metabolic characteristics in the peri-diagnostic period of T1D. Mixed meal tolerance tests (MMTT) were performed within 6 months (median: 2 months, range: 4 days - 6 months) following diagnosis and then every 5-6 months in the first 3 years after diagnosis. Race and ethnicity categories were based on self-report and on standard NIH classifications. Unless otherwise indicated, all analyses were adjusted for age, age and sex-adjusted BMI Z-score, sex, as well as days from diagnosis to MMTT. Median ages (IQR) at enrollment were 14.1(6) years in Hispanics and 14.3(7.5) years in NHW. 44.7% of Hispanics and 41.8% of NHW were female. At T1D clinical diagnosis, Hispanics, compared with NHW, had a higher frequency of diabetic ketoacidosis [DKA] (42.9% vs. 22.8%, OR=2.45, p=0.008), lower fasting glucose (97.5 vs. 108.5 mg/dL, p=0.011), higher frequency of ZnT8 autoantibody positivity (n=201, 94.1% vs. 63.5%, p=0.039), and a trend for higher fasting C-peptide (0.39 vs. 0.32 ng/mL, p=0.093). When analyzing C-peptide trajectories by ethnicity in eligible participants (n=310), there were no significant differences during 3-year follow-up after adjusting for BMI-Z score and age (mean C-peptide AUC, p=0.74).

In conclusion, despite ethnic differences in the frequency of DKA, and metabolic and immunological characteristics at clinical diagnosis of T1D, C-peptide trajectories did not differ in the first 3 years following diagnosis between Hispanics and NHW. These findings may inform the design of observational studies and intervention trials in the peri-diagnostic period of T1D.