The incidence of and susceptibility to Type 2 diabetes increases with age, but the underlying mechanism(s) within beta cells that contribute to this increased susceptibility have not been fully elucidated. Here we review how aging affects the proliferative and regenerative capacity of beta cells and how this impacts beta cell mass. In addition we review changes that occur in beta cell function with age. Although we focus on the different rodent models that have provided insight into the characteristics of the aging beta cell, the limited knowledge from non-rodent models is also reviewed. Further studies are needed in order to identify potential beta cell targets for preventing or slowing the progression of diabetes that occurs with age.
Type 1 and type 2 diabetes result from an absolute or relative reduction in functional β-cell mass. One approach to replacing lost β-cell mass is transplantation of cadaveric islets; however, this approach is limited by lack of adequate donor tissue. Therefore, there is much interest in identifying factors that enhance β-cell differentiation and proliferation in vivo or in vitro. Connective tissue growth factor (CTGF) is a secreted molecule expressed in endothelial cells, pancreatic ducts, and embryonic β cells that we previously showed is required for β-cell proliferation, differentiation, and islet morphogenesis during development. The current study investigated the tissue interactions by which CTGF promotes normal pancreatic islet development. We found that loss of CTGF from either endothelial cells or β cells results in decreased embryonic β-cell proliferation, making CTGF unique as an identified β cell-derived factor that regulates embryonic β-cell proliferation. Endothelial CTGF inactivation was associated with decreased islet vascularity, highlighting the proposed role of endothelial cells in β-cell proliferation. Furthermore, CTGF overexpression in β cells during embryogenesis using an inducible transgenic system increased islet mass at birth by promoting proliferation of immature β cells, in the absence of changes in islet vascularity. Together, these findings demonstrate that CTGF acts in an autocrine manner during pancreas development and suggest that CTGF has the potential to enhance expansion of immature β cells in directed differentiation or regeneration protocols.
Diabetes results from an inadequate functional β cell mass, either due to autoimmune destruction (Type 1 diabetes) or insulin resistance combined with β cell failure (Type 2 diabetes). Strategies to enhance β cell regeneration or increase cell proliferation could improve outcomes for patients with diabetes. Research conducted over the past several years has revealed that factors regulating embryonic β cell mass expansion differ from those regulating replication ofβ cells post-weaning. This article aims to compare and contrast factors known to control embryonic and postnatal β cell replication. In addition, we explore the possibility that connective tissue growth factor (CTGF) could increase adult β cell replication. We have already shown that CTGF is required for embryonicβ cell proliferation and is sufficient to induce replication of embryonic β cells. Here we examine whether adult β cell replication and expansion of β cell mass can be enhanced by increased CTGF expression in mature β cells.
Aim: To compare the efficacy and safety of a glucagon-like peptide-1 receptor agonist (GLP1RA) plus basal insulin versus basal-bolus insulin treatment in patients with very uncontrolled type 2 diabetes.
Materials and methods:The SIMPLE study was a 6-month pragmatic, randomized, open-label trial testing the effectiveness of two approaches to treat patients with type 2 diabetes and HbA1c ≥10%. We randomized patients to detemir plus liraglutide or detemir plus aspart (before each meal). The primary endpoint was change in HbA1c; changes in body weight, insulin dose, hypoglycaemia and diabetes-related quality-of-life were secondary outcomes.Results: We randomized 120 participants aged 47.4 ± 9.5 years, Hispanic 40%, African American 42%, diabetes duration 10 [25th-75th percentile (6 to 15)] years, body mass index 37.2 ± 10.3 kg/m 2 . HbA1c decreased more with GLP1RA plus basal insulin [12.2% (95% CI 11.8% to 12.6%) to 8.1% (95% CI 7.4% to 8.7%)] compared with basal-bolus insulin [11.8% (95% CI 11.5% to 12.2%) to 8.8% (95% CI 88.1% to 9.55%)]; estimated treatment difference (ETD) of −1.1% (95% CI −2.0% to −0.1%) (non-inferiority margin 0.4% and P = .0001, superiority P = .026). Compared with basal-bolus insulin, treatment with GLP1RA plus basal insulin led to a body weight ETD of −3.7 kg (95% CI −5.8 to −1.5; P = .001), fewer patients experiencing hypoglycaemia [66.1% vs 35.2% (P = .002)], and greater improvements in general/current health perception, treatment satisfaction, and fear of hypoglycaemia, while taking a lower total daily dose of insulin [estimated treatment ratio 0.68 (95% CI 0.55 to 0.84)].Conclusions: In patients with HbA1c ≥10% treatment with GLP1RA plus basal insulin, compared with basal-bolus insulin, resulted in better glycaemic control and body weight, lower insulin dosage and hypoglycaemia, and improved quality of life. This treatment strategy is an effective and safe alternative to a basal-bolus insulin regimen.
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