The islets of Langerhans in the pancreas play a central role in glucose homeostasis, and are therefore critical to the pathophysiology of diabetes. However, the size, endocrine cell composition and number of islets in healthy individuals and those with diabetes (type 1 and type 2) have not been fully documented. Rippa and colleagues addressed this gap by performing 3D analyses of pancreata from non-diabetic individuals, those with short-duration type 1 diabetes and those at risk of type 1 diabetes. 

These analyses revealed that approximately 50% of islets in non-diabetic pancreata are insulin-positive (INS⁺) and glucagon-negative (GCG^–). Notably, despite their increased risk of developing type 1 diabetes, individuals without diabetes who are positive for a single glutamic acid decarboxylase autoantibody (GADA⁺) display endocrine features (including total islet volume and cellular composition) that closely resemble those of age-matched non-diabetic controls. In contrast, pancreata from individuals with short-duration type 1 diabetes exhibit a marked reduction in islet density, accompanied by a substantial loss of INS⁺GCG^– islets and relative preservation of larger INS⁺GCG⁺ islets. 

Collectively, these findings suggest that pancreatic islet size and endocrine cell composition are key determinants of β cell vulnerability and loss during the progression of type 1 diabetes.

Read the full article in Nature Communications https://doi.org/10.1038/s41467-025-66198-6