CONTEXT: There are interplays between the endocrine and exocrine pancreas. We have recently reported an increased frequency of exocrine dysfunction in HNF1A-MODY (MODY3) patients compared to controls. Reduced pancreatic volume is seen in HNF1B-MODY (MODY5) and in diabetes type 1 and 2.

OBJECTIVE: The aim of this study was to investigate whether HNF1A mutation carriers have reduced pancreatic volume or abnormal pancreatic structure, and whether any changes are associated with exocrine dysfunction.

METHODS: Fifteen HNF1A mutation carriers recruited from the Norwegian MODY Registry, 31 subjects with type 1 diabetes, 10 subjects with type 2 diabetes and 11 controls underwent computed tomography of the pancreas. We measured pancreatic volume and X-ray attenuation. Pancreatic volume index was defined as pancreatic volume divided by body surface area.

RESULTS: Pancreatic volume index was reduced in subjects with HNF1A-MODY (34.5 mL/m²; P < 0.02) and type 1 diabetes (21.4 mL/m²; P < 0.001) as compared to non-diabetic controls (45.7 mL/m²), and was reduced in subjects with diabetes in combination with fecal elastase deficiency (P= 0.03). Subjects with type 1 diabetes had smaller pancreatic volume index compared to HNF1A mutation carriers (P < 0.001). Reduced pancreatic volume index was associated with increasing duration of diabetes. Pancreatic X-ray attenuation in HNF1A mutation carriers was not significantly different from that of non-diabetic controls.

CONCLUSIONS: HNF1A mutation carriers have reduced pancreatic volume, but less reduced than in patients with type 1 diabetes. Insulinopenia could explain both the pancreatic volume reduction and the associated pancreatic dysfunction.