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Objective The aim was to investigate whether vitamin D supplementation, combined with a hypocaloric diet, could have an independent effect on insulin sensitivity in subjects with both overweight and hypovitaminosis D. Changes from baseline in anthropometric parameters, body composition, glucose tolerance, and insulin secretion were considered as secondary outcomes. Methods Eighteen volunteers who were nondiabetic and vitamin D deficient and had BMI > 25 kg/m2 were randomized (1:1) in a double-blind manner to a hypocaloric diet + either oral cholecalciferol at 25,000 IU/wk or placebo for 3 months. Hyperinsulinemic-euglycemic clamp to measure insulin sensitivity was performed at baseline and after intervention. Results Body weight in both groups decreased significantly (−7.5% in the vitamin D group and −10% in the placebo group; P

CONTEXT: Insulin resistance impacts virtually all tissues, including pancreatic β cells. Individuals with insulin resistance, but without diabetes, exhibit an increased islet size because of an elevated number of both β and α cells. Neogenesis from duct cells and transdifferentiation of α cells have been postulated to contribute to the β-cell compensatory response to insulin resistance. OBJECTIVE: Our objective was to explore parameters that could potentially predict altered islet morphology. METHODS: We investigated 16 nondiabetic subjects by a 2-hour hyperglycemic clamp to evaluate β-cell secretory function. We analyzed pancreas samples obtained during pancreatoduodenectomy in the same patients to examine glucagon and insulin double+ cells to assess islet morphology. RESULTS: Among all the functional in vivo parameters of insulin secretion that were explored (basal, first phase and total secretion, glucose sensitivity, arginine-stimulated insulin secretion), β-cell glucose sensitivity was unique in exhibiting a significant correlation with both islet size and α-β double+ islet cells. CONCLUSIONS: Our data suggest that poor β-cell glucose sensitivity is linked to islet transdifferentiation, possibly from α cells to β cells, in an attempt to cope with higher demands for insulin secretion. Understanding the mechanism(s) that underlies the adaptive response of the islet cells to insulin resistance is a potential approach to design tools to enhance functional β-cell mass for diabetes therapy.

Background Pancreaticoduodenectomy represents the major treatment for pancreatic and periampullary neoplasms. Complications related to pancreaticojejunostomy are still the leading cause of morbidity and mortality. A solution proposed by some surgeons is the occlusion of main pancreatic duct by acrylic glue, avoiding pancreaticojejunostomy. Nevertheless, the consequences of this procedure on glucose metabolism are not well-defined. Methods We retrospectively analyzed a cohort of 50 patients who underwent pancreaticoduodenectomy and had metabolic assessments available. The metabolic evaluation included the following: body composition and clinical evaluation, an oral glucose tolerance test, and an hyperinsulinemic euglycemic clamp procedure. Results Twenty-three patients underwent pancreatic duct occlusion and were compared with 27 patients, well-matched controls, who underwent pancreaticojejunostomy. Pancreatic duct occlusion leads to a greater impairment in insulin secretion compared with classic pancreaticojeunostomy. Conclusion Pancreatic duct occlusion is associated with a greater reduction in insulin secretion but does not lead to meaningful differences in the management of patients with diabetes.