349-OR: Pancreas Volume Is Smaller in Individuals with Stage 1 Type 1 Diabetes (T1D) and Correlates with Disease Progression

Pancreas size is smaller at the onset of T1D and in individuals at risk for T1D, as measured by MRI. To determine whether pancreas volume predicts T1D progression, we measured pancreas size and dynamics in Type 1 Diabetes TrialNet Pathway to Prevention study participants with Stage 1 T1D, as defined by the presence of two or more autoantibodies and normal glucose tolerance. Individuals with Stage 1 T1D (n = 25, median age = 13.9 y.o.) exhibited a smaller pancreas volume than controls without T1D (n = 34, median age = 15.2 y.o, p < 0.001), but larger than individuals with Stage 3 T1D (n = 67, median age = 13.4 y.o, p < 0.05). This intermediate pancreas size in individuals with Stage 1 T1D persisted when pancreas volume was normalized by either body weight (pancreas volume index) or BMI. There was no correlation between the number or specificity of autoantibodies expressed and the pancreas volume index. Using longitudinal pancreas MRI in 25 autoantibody-positive individuals (total of 80 MRIs), we found that pancreas volume was stable over time, with no increase or decrease up to three years after the initial MRI (95% CI of slope: -0.094 to 0.5788 ml/month). Two of the 25 autoantibody-positive participants who developed Stage 3 T1D during follow up had the smallest pancreas volume index at study entry (0.43 +/- 0.04 ml/kg, p < 0.005 compared with those who did not progress to Stage 3). An additional 11 of the 25 participants developed impaired glucose tolerance during follow up. Initial pancreas volume index in the 13 total participants who developed Stage 2 or Stage 3 T1D (0.75 +/- 0.06 ml/kg) was significantly smaller (p < 0.05) than the 12 participants who retained normal glucose tolerance over the course of the study (0.95 +/- 0.05 ml/kg). These data suggest that small pancreas size may be predictive of progression of T1D. Disclosure J. Virostko: None. J.M. Williams: None. M.A. Hilmes: None. J.J. Wright: None. B.D. Hammel: None. L. Du: None. H. Kang: None. W.E. Russell: None. A.C. Powers: None. D.J. Moore: None. Funding JDRF (3-SRA-2019-759-M-B, 3-SRA-2015-102-M-B)