Meal-dependent regulation of circulating glycated insulin in type 2 diabetic subjects

Optimising insulin aspart practices in a neonatal intensive care unit: a clinical and pharmaco-technical study

Neonatal hyperglycaemia is frequent and requires insulin therapy. To resolve the difficulties encountered by paediatricians in stabilising glycaemia, the preparation and administration of insulin aspart were assessed and optimised. After high-performance liquid chromatography (HPLC-UV) assessment of insulin aspart preparations made according to the old protocol, a new protocol was drawn up. Dosage reliability of solutions prepared by paediatric nurses was evaluated by HPLC-UV. This new protocol was also tested in a Y-infusion situation and the need to saturate infusion tubes assessed. Wide deviations in insulin aspart concentrations were found between theoretical concentrations and preparations made according to the old protocol. Glycated insulin aspart was found in the majority of these preparations. The new protocol significantly reduced the variability of data and relative deviations around the target value. It also eliminated the formation of glycated insulin even in the case of co-infusion of parenteral nutrition and confirmed the need to saturate infusion tubes.Conclusion: The revision of the insulin therapy protocol reduced the variability of insulin concentration in preparations and avoided the administration of glycated derivatives potentially toxic for neonates. What is Known: • Insulin preparation in NICUs is a risky task because it is a two-step preparation • Diluted in dextrose, insulin aspart is unstable, with formation of potentially toxic glycated derivatives What is New: • This work proposes a new insulin therapy protocol validated by HPLC-UV for NICU allowing suppression of the formation of glycated insulin, to significantly reduce deviations from theoretical concentrations and to limit adsorption phenomena • This protocol is validated in case of co-infusion of parenteral nutrition.

Wnt Glycation Inhibits Canonical Signaling

Glycation occurs as a non-enzymatic reaction between amino and thiol groups of proteins, lipids, and nucleotides with reducing sugars or α-dicarbonyl metabolites. The chemical reaction underlying is the Maillard reaction leading to the formation of a heterogeneous group of compounds named advanced glycation end products (AGEs). Deleterious effects have been observed to accompany glycation such as alterations of protein structure and function resulting in crosslinking and accumulation of insoluble protein aggregates. A substantial body of evidence associates glycation with aging. Wnt signaling plays a fundamental role in stem cell biology as well as in regeneration and repair mechanisms. Emerging evidence implicates that changes in Wnt/β-catenin pathway activity contribute to the aging process. Here, we investigated the effect of glycation of Wnt3a on its signaling activity. Methods: Glycation was induced by treatment of Wnt3a-conditioned medium (CM) with glyoxal (GO). Effects on Wnt3a signaling activity were analyzed by Topflash/Fopflash reporter gene assay, co-immunoprecipitation, and quantitative RT-PCR. Results: Our data show that GO-treatment results in glycation of Wnt3a. Glycated Wnt3a suppresses β-catenin transcriptional activity in reporter gene assays, reduced binding of β-catenin to T-cell factor 4 (TCF-4) and extenuated transcription of Wnt/β-catenin target genes. Conclusions: GO-induced glycation impairs Wnt3a signaling function.

An emerging role of glucagon-like peptide-1 in preventing advanced-glycation-end-product-mediated damages in diabetes

Glucagon-like peptide-1 (GLP-1) is a gut hormone produced in the intestinal epithelial endocrine L cells by differential processing of the proglucagon gene. Released in response to the nutrient ingestion, GLP-1 plays an important role in maintaining glucose homeostasis. GLP-1 has been shown to regulate blood glucose levels by stimulating glucose-dependent insulin secretion and inhibiting glucagon secretion, gastric emptying, and food intake. These antidiabetic activities highlight GLP-1 as a potential therapeutic molecule in the clinical management of type 2 diabetes, (a disease characterized by progressive decline of beta-cell function and mass, increased insulin resistance, and final hyperglycemia). Since chronic hyperglycemia contributed to the acceleration of the formation of Advanced Glycation End-Products (AGEs, a heterogeneous group of compounds derived from the nonenzymatic reaction of reducing sugars with free amino groups of proteins implicated in vascular diabetic complications), the administration of GLP-1 might directly counteract diabetes pathophysiological processes (such as pancreatic β-cell dysfunction). This paper outlines evidence on the protective role of GLP-1 in preventing the deleterious effects mediated by AGEs in type 2 diabetes.