Pancreas Volume Declines over the First Year after Diagnosis with Type 1 Diabetes (T1D)

The pancreas is smaller in individuals with T1D, but it is unclear if these individuals are born with a smaller pancreas or whether their pancreatic volume declines as part of disease progression. To determine the dynamics of pancreas volume in new-onset T1D, we performed longitudinal magnetic resonance imaging (MRI) of the pancreas in individuals with recent-onset T1D (n = 51, mean age 13.7 y, range 8-24 y) within the first 100 days after diagnosis (mean 67 days), six months after diagnosis, and one year post diagnosis. In agreement with and extension of our results presented at 2017 ADA Scientific Sessions, we found that at disease onset, young individuals with T1D had a smaller pancreas (median volume = 29.6 ml) than similarly aged controls (median volume = 49.6 ml, n = 51, p < 0.001). Pancreas volume was lower in T1D individuals when normalized by subject weight (p < 0.001), as well as when adjusted for age, gender and body mass index (p < 0.001). Longitudinal measurements of pancreas volume increased in controls over the year, corresponding with adolescent growth, but pancreas volume declined over the first year after T1D diagnosis (p < 0.001). Pancreas volume measurements normalized by body weight were stable in controls, but declined in subjects with T1D (p < 0.001). We also performed MRI in 14 individuals enrolled in TrialNet with multiple autoantibodies portending the development of T1D, and found that pancreas volume was similar to controls (median volume = 59.1 ml), but significantly greater than the T1D cohort (p < 0.001). To interrogate microstructural changes in the pancreas, we performed diffusion-weighted MRI and found that individuals with recent-onset T1D had a higher apparent diffusion coefficient (p = 0.023), indicating reduced restrictions on water diffusion in the pancreas in T1D. These results indicate the existence of ongoing pancreatic atrophy during the first year after diagnosis with T1D which may be reflected by microstructural changes in the pancreas.