medwireNews: Individuals with recently diagnosed type 1 diabetes, as well as their first-degree relatives, have significantly smaller pancreases than individuals with no history of diabetes, show two studies published in Diabetes Care.
In the first study, John Virostko (University of Texas at Austin, USA) and colleagues showed that people with recent-onset type 1 diabetes (n=51; median age 13 years) had a significantly smaller pancreas volume than 57 similarly aged controls, when measured by magnetic resonance imaging (MRI) within 100 days of diagnosis (median 28.6 vs 48.4 mL).
And the difference remained significant, at a median 13.9 mL lower in participants with diabetes than in controls, after adjustment for BMI.
Furthermore, individuals without diabetes but positive for multiple autoantibodies (n=20) had an intermediate pancreas volume that was significantly larger than that of the group with diabetes, but significantly smaller than that observed in the controls.
Virostko and team also measured changes in pancreas volume over time and recorded an average increase of 0.7% per month in the control group, which they say is “consistent with adolescent growth,” but an average decrease of 0.6% per month for the first year among the participants with diabetes.
The researchers found no correlation between pancreas volume and markers of glycemic control, but they note that the individuals with diabetes had a significantly higher apparent diffusion coefficient on diffusion-weighted MRI compared with the controls, which suggests “a loss of cellular structural integrity, with heterogeneous pancreatic distribution,” they remark.
Virostko and co-authors conclude that their study raises “fundamental questions that challenge our understanding of [type 1 diabetes] pathogenesis and its β-cell–specific nature.”
They are currently undertaking further studies in the diabetes and autoantibody-positive cohorts “to fully characterize the time course of pancreas volume in the natural history of [type 1 diabetes].”
In the second study, Martha Campbell-Thompson (University of Florida, Gainesville, USA) and colleagues also used MRI to investigate pancreas volume, this time in patients with diabetes (n=52, mean age 16.2 years), their first-degree relatives with (n=67) and without (n=61) autoantibodies, and in an autoantibody-negative control group with no first- or second-degree relatives with type 1 diabetes (n=49).
They found that relative pancreas volume adjusted for BMI was significantly lower in the first-degree relatives than controls, regardless of autoantibody status, and was significantly lower again in the patients with type 1 diabetes.
“These findings bring renewed interest to the complexity of interactions between the pancreatic endocrine-exocrine compartments in type 1 diabetes and monogenic diabetes,” Campbell-Thompson et al remark.
“They also raise a novel hypothesis that a smaller pancreas in [first-degree relatives] may act as a predisposing factor for type 1 diabetes risk, particularly if exocrine and endocrine mass reductions occur in parallel.”
However, the team concludes that further studies are needed before pancreas volume can be used to predict progression to type 1 diabetes.
By Laura Cowen
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