Metformin and Glucose Concentration as Limiting Factors in Retinal Pigment Epithelial Cell Viability and Proliferation.

Metformin is a well-established drug for the treatment of type 2 diabetes; however, the mechanism of action has not been well described and many aspects of how it truly acts are still unknown. Moreover, regarding in vitro experiments, the glycaemic status when metformin is used is generally not considered, which, added to the suprapharmacological drug concentrations that are commonly employed in research, has resulted in gaps of its mechanism of action. The aim of this study was to determine how glucose and metformin concentrations influence cell culture. Considering that diabetic retinopathy is one of the most common complications of diabetes, a retinal pigment epithelial cell line was selected, and cell viability and proliferation rates were measured at different glucose and metformin concentrations. As expected, glucose concentration by itself positively influenced cell proliferation rates. When the metformin was considered, results were conditioned, as well, by metformin concentration. This conditioning resulted in cell death when high concentrations of metformin were used under physiological concentrations of glucose, while this did not happen when clinically relevant concentrations of metformin were used independently of glucose status. Our study shows the importance of in vitro cell growth conditions when drug effects such as metformin's are being analysed.

Hypoglycemia during hyperosmolar hyperglycemic crises is associated with long-term mortality.

BACKGROUND: Previous research has indicated that hypoglycemia during hospitalization is a predictor of unfavorable outcomes in patients with diabetes. However, no studies have examined the long-term impact of hypoglycemia in adults admitted for hyperglycemic crises. The study was aimed to investigate the long-term implications of hypoglycemia during hyperosmolar hyperglycemic crises, particularly in terms of all-cause mortality. METHODS: This retrospective cohort study included 170 patients (82 men [48.2%], median age 72 years) admitted to a university hospital for hyperosmolar hyperglycemic crises, including pure hyperosmolar hyperglycemic states and hyperosmolar diabetic ketoacidoses. We separately investigated the prognostic significance of hypoglycemia on mortality during the initial intravenous insulin therapy phase and during the later subcutaneous insulin therapy phase, both during hospitalization and in the long term (median follow-up, 652 days; range 2-3460 days). RESULTS: Both hypoglycemia during the initial intravenous insulin therapy phase (observed in 26.5% of patients) and hypoglycemia during the later subcutaneous insulin therapy phase (observed in 52.7% of patients) were associated with long-term mortality. After adjusting for potential confounders, hypoglycemia during the initial intravenous insulin therapy phase remained associated with mortality (hazard ratio 2.10, 95% CI 1.27-3.46, p = 0.004). CONCLUSIONS: Hypoglycemia during hyperosmolar hyperglycemic crises is a marker of long-term mortality, especially when it occurs during the initial intravenous insulin therapy phase.

Circulating miRNA expression in long-standing type 1 diabetes mellitus.

Type 1 diabetes is a chronic autoimmune disease which results in inefficient regulation of glucose homeostasis and can lead to different vascular comorbidities through life. In this study we aimed to analyse the circulating miRNA expression profile of patients with type 1 diabetes, and with no other associated pathology. For this, fasting plasma was obtained from 85 subjects. Next generation sequencing analysis was firstly performed to identify miRNAs that were differentially expressed between groups (20 patients vs. 10 controls). hsa-miR-1-3p, hsa-miR-200b-3p, hsa-miR-9-5p, and hsa-miR-1200 expression was also measured by Taqman RT-PCR to validate the observed changes (34 patients vs. 21 controls). Finally, through a bioinformatic approach, the main pathways affected by the target genes of these miRNAs were studied. Among the studied miRNAs, hsa-miR-1-3p expression was found significantly increased in patients with type 1 diabetes compared to controls, and positively correlated with glycated haemoglobin levels. Additionally, by using a bioinformatic approach, we could observe that changes in hsa-miR-1-3p directly affect genes involved in vascular development and cardiovascular pathologies. Our results suggest that, circulating hsa-miR-1-3p in plasma, together with glycaemic control, could be used as prognostic biomarkers in type 1 diabetes, helping to prevent the development of vascular complications in these patients.