BACKGROUND & AIMS Glucagon-like peptide-1–based therapy is gaining widespread use for type 2 diabetes, although there are concerns about risks for pancreatitis and pancreatic and thyroid cancers. There are also concerns that dipeptidyl peptidase-4 inhibitors could cause cancer, given their effects on immune function. METHODS We examined the US Food and Drug Administration’s database of reported adverse events for those associated with the dipeptidyl peptidase–4 inhibitor sitagliptin and the glucagon-like peptide-1 mimetic exenatide, from 2004–2009; data on adverse events associated with 4 other medications were compared as controls. The primary outcomes measures were rates of reported pancreatitis, pancreatic and thyroid cancer, and all cancers associated with sitagliptin or exenatide, compared with other therapies. RESULTS Use of sitagliptin or exenatide increased the odds ratio for reported pancreatitis 6-fold as compared with other therapies (P < 2 × 10−16). Pancreatic cancer was more commonly reported among patients who took sitagliptin or exenatide as compared with other therapies (P < .008, P < 9 × 10−5). All other cancers occurred similarly among patients who took sitagliptin compared with other therapies (P =.20). CONCLUSIONS These data are consistent with case reports and animal studies indicating an increased risk for pancreatitis with glucagon-like peptide-1–based therapy. The findings also raise caution about the potential long-term actions of these drugs to promote pancreatic cancer.

Adipose tissue inflammation and dysfunction are associated with obesity‐related insulin resistance and diabetes, but mechanisms underlying this relationship are unclear. Although senescent cells accumulate in adipose tissue of obese humans and rodents, a direct pathogenic role for these cells in the development of diabetes remains to be demonstrated. Here, we show that reducing senescent cell burden in obese mice, either by activating drug‐inducible “suicide” genes driven by the p16Ink4a promoter or by treatment with senolytic agents, alleviates metabolic and adipose tissue dysfunction. These senolytic interventions improved glucose tolerance, enhanced insulin sensitivity, lowered circulating inflammatory mediators, and promoted adipogenesis in obese mice. Elimination of senescent cells also prevented the migration of transplanted monocytes into intra‐abdominal adipose tissue and reduced the number of macrophages in this tissue. In addition, microalbuminuria, renal podocyte function, and cardiac diastolic function improved with senolytic therapy. Our results implicate cellular senescence as a causal factor in obesity‐related inflammation and metabolic derangements and show that emerging senolytic agents hold promise for treating obesity‐related metabolic dysfunction and its complications.

OBJECTIVE-Type 2 diabetes is characterized by impaired insulin secretion in response to increased metabolic demand. This defect in ␤-cell compensation seems to result from the interplay between environmental factors and genetic predisposition. Genome-wide association studies reveal that common variants in transcription factor 7-like 2 (TCF7L2) are associated with increased risk of type 2 diabetes. The aim of the present study was to establish whether TCF7L2 plays a role in ␤-cell function and/or survival. RESEARCH DESIGN AND METHODS-To investigate the effects of TCFL7L2 depletion, isolated islets were exposed to TCF7L2 small interfering RNA (siRNA) versus scrambled siRNA, and ␤-cell survival and function were examined. For TCF7L2 overexpression, islets were cultured in glucose concentrations of 5.5-33.3 mmol/l and the cytokine mix interleukin-1␤/␥-interferon with or without overexpression of TCF7L2. Subsequently, glucose-stimulated insulin secretion (GSIS), ␤-cell apoptosis [by transferase-mediated dUTP nick-end labeling assay and Western blotting for poly(ADP-ribose) polymerase and Caspase-3 cleavage], and ␤-cell proliferation (by Ki67 immunostaining) were analyzed. RESULTS-DepletingTCF7L2 by siRNA resulted in a 5.1-fold increase in ␤-cell apoptosis, 2.2-fold decrease in ␤-cell proliferation (P Ͻ 0.001), and 2.6-fold decrease in GSIS (P Ͻ 0.01) in human islets. Similarly, loss of TCF7L2 resulted in impaired ␤-cell function in mouse islets. In contrast, overexpression of TCF7L2 protected islets from glucose and cytokine-induced apoptosis and impaired function. CONCLUSIONS-TCF7L2is required for maintaining GSIS and ␤-cell survival. Changes in the level of active TCF7L2 in ␤-cells from carriers of at-risk allele may be the reason for defective insulin secretion and progression of type 2 diabetes. Diabetes 57: [645][646][647][648][649][650][651][652][653] 2008

Pancreatic duct glands (PDGs) have been hypothesized to give rise to pancreatic intraepithelial neoplasia (PanIN). Treatment with the glucagon-like peptide (GLP)-1 analog, exendin-4, for 12 weeks induced the expansion of PDGs with mucinous metaplasia and columnar cell atypia resembling low-grade PanIN in rats. In the pancreata of Pdx1-Cre; LSL-KrasG12D mice, exendin-4 led to acceleration of the disruption of exocrine architecture and chronic pancreatitis with mucinous metaplasia and increased formation of murine PanIN lesions. PDGs and PanIN lesions in rodent and human pancreata express the GLP-1 receptor. Exendin-4 induced proproliferative signaling pathways in human pancreatic duct cells, cAMP–protein kinase A and mitogen-activated protein kinase phosphorylation of cAMP-responsive element-binding protein, and increased cyclin D1 expression. These GLP-1 effects were more pronounced in the presence of an activating mutation of Kras and were inhibited by metformin. These data reveal that GLP-1 mimetic therapy may induce focal proliferation in the exocrine pancreas and, in the context of exocrine dysplasia, may accelerate formation of neoplastic PanIN lesions and exacerbate chronic pancreatitis.

OBJECTIVEWe sought to establish the extent and mechanisms by which sitagliptin and metformin singly and in combination modify islet disease progression in human islet amyloid polypeptide transgenic (HIP) rats, a model for type 2 diabetes.RESEARCH DESIGN AND METHODSHIP rats were treated with sitagliptin, metformin, sitagliptin plus metformin, or no drug as controls for 12 weeks. Fasting blood glucose, insulin sensitivity, and β-cell mass, function, and turnover were measured in each group.RESULTSSitagliptin plus metformin had synergistic effects to preserve β-cell mass in HIP rats. Metformin more than sitagliptin inhibited β-cell apoptosis. Metformin enhanced hepatic insulin sensitivity; sitagliptin enhanced extrahepatic insulin sensitivity with a synergistic effect in combination. β-Cell function was partially preserved by sitagliptin plus metformin. However, sitagliptin treatment was associated with increased pancreatic ductal turnover, ductal metaplasia, and, in one rat, pancreatitis.CONCLUSIONSThe combination of metformin and sitagliptin had synergistic actions to preserve β-cell mass and function and enhance insulin sensitivity in the HIP rat model of type 2 diabetes. However, adverse actions of sitagliptin treatment on exocrine pancreas raise concerns that require further evaluation.