Predictors of postpartum diabetes in women with gestational diabetes mellitus.

The aim of this study was to stratify risk for postpartum diabetes in women who have gestational diabetes. Women with gestational diabetes were recruited between 1989 and 1999, and 302 were followed with oral glucose tolerance tests at 9 months and 2, 5, 8, and 11 years postpregnancy. The 8-year postpartum diabetes risk was 52.7% (130 diabetic cases). Risk was increased in women with autoantibodies to GAD and/or insulinoma antigen-2 (adjusted hazard ratio 4.1; P < 0.0001), women who required insulin during pregnancy (4.7; P < 0.0001), women with BMI >30 kg/m2 (1.5; P = 0.04), and women with more than two prior pregnancies (2.5; P = 0.02). Women without these risk factors had a postpartum diabetes risk of 14% by 8 years, and risk rose incrementally to 96% by 8 years in autoantibody-positive women. Parity status, C-reactive protein concentration, a diabetes family history, maternal age, weeks of gestation, and the child's birth weight did not significantly affect risk in multivariate analysis. Prospective diabetes assessment is indicated and intervention should be considered in women with gestational diabetes who are autoantibody positive, require insulin treatment during pregnancy, or are obese.

The development of new density gradient media for purifying human islets and islet-quality assessments.

Successful islet transplantation is dependent on the quality and quantity of islets infused. Islets are purified on density gradients, but procedures currently used have limited capacity for pancreatic digests, islet yield, and viability. We aimed to improve islet purification with a modified gradient medium. Biocoll was diluted in University of Wisconsin solution to create linear density gradients of 1.065 to 1.095 g/mL. Properties of islets purified from 22 human pancreas digests with modified medium were compared with 15 preparations using standard medium. The modification increased the capacity of gradients for pancreatic digests from 20 to 60 mL, islet yield increased from 218,000 to 435,318 per isolation, and viability increased from 65.4% to 92.1%. Islet fractions contained greater than 95% of recovered insulin. Islets showed good physiologic responses to secretagogues and restored normoglycemia in streptozotocin-induced diabetic severe combined immunodeficiency disease mice. The new medium enhances yield, purity, and viability of human islet preparations for clinical islet transplantation.

Different regulated expression of the tyrosine phosphatase-like proteins IA-2 and phogrin by glucose and insulin in pancreatic islets: relationship to development of insulin secretory responses in early life.

IA-2 and phogrin are tyrosine phosphatase-like proteins that may mediate interactions between secretory granules and cytoskeleton in islets and neuroendocrine tissues. We investigated factors that regulate IA-2 and phogrin expression and their relationship to maturation of insulin secretory responses that occur after birth. Islet content of IA-2, but not phogrin, increased during the first 10 days of life in rats, when insulin secretion in response to glucose increased to adult levels. In cultured 5-day-old rat islets, IA-2 protein and mRNA was increased by glucose and agents that potentiate insulin secretion by the cAMP pathway. Addition of insulin increased IA-2 protein levels and insulin biosynthesis without affecting IA-2 mRNA. Blocking insulin secretion with diazoxide or insulin action with insulin receptor antibodies inhibited glucose-induced increases in IA-2 protein, but not those of mRNA. Phogrin expression was unchanged by all agents. Thus, IA-2 is regulated at the mRNA level by glucose and elevated cAMP, whereas locally secreted insulin modulates IA-2 protein levels by stimulating biosynthesis. In contrast, phogrin expression is insensitive to factors that modify beta-cell function. These results demonstrate differential regulation of two closely related secretory granule components and identify IA-2 as a granule membrane protein subject to autocrine regulation by insulin.