The Role of Glucagon in Glycemic Variability in Type 1 Diabetes: A Narrative Review

Decoding the Significance of Alpha Cell Function in the Pathophysiology of Type 1 Diabetes

Alpha cells in the pancreas, traditionally known for their role in secreting glucagon to regulate blood glucose levels, are gaining recognition for their involvement in the pathophysiology of type 1 diabetes (T1D). In T1D, autoimmune destruction of beta cells results in insulin deficiency, which in turn may dysregulate alpha cell function, leading to elevated glucagon levels and impaired glucose homeostasis. This dysfunction is characterized by inappropriate glucagon secretion, augmenting the risk of life-threatening hypoglycemia. Moreover, insulin deficiency and autoimmunity alter alpha cell physiological responses, further exacerbating T1D pathophysiology. Recent studies suggest that alpha cells undergo transdifferentiation and interact with beta cells through mechanisms involving gamma-aminobutyric acid (GABA) signaling. Despite these advances, the exact pathways and interactions remain poorly understood and are often debated. Understanding the precise role of alpha cells in T1D is crucial, as it opens up avenues for developing new therapeutic strategies for T1D. Potential strategies include targeting alpha cells to normalize glucagon secretion, utilizing glucagon receptor antagonists, enhancing GABA signaling, and employing glucagon-like peptide-1 (GLP-1) receptor agonists. These approaches aim to improve glycemic control and reduce the risk of hypoglycemic events in individuals with T1D. This review provides an overview of alpha cell function in T1D, highlighting the emerging focus on alpha cell dysfunction in the context of historically well-developed beta cell research.

Glycolytic enzymes in non-glycolytic web: functional analysis of the key players

To survive in the tumour microenvironment, cancer cells undergo rapid metabolic reprograming and adaptability. One of the key characteristics of cancer is increased glycolytic selectivity and decreased oxidative phosphorylation (OXPHOS). Apart from ATP synthesis, glycolysis is also responsible for NADH regeneration and macromolecular biosynthesis, such as amino acid biosynthesis and nucleotide biosynthesis. This allows cancer cells to survive and proliferate even in low-nutrient and oxygen conditions, making glycolytic enzymes a promising target for various anti-cancer agents. Oncogenic activation is also caused by the uncontrolled production and activity of glycolytic enzymes. Nevertheless, in addition to conventional glycolytic processes, some glycolytic enzymes are involved in non-canonical functions such as transcriptional regulation, autophagy, epigenetic changes, inflammation, various signaling cascades, redox regulation, oxidative stress, obesity and fatty acid metabolism, diabetes and neurodegenerative disorders, and hypoxia. The mechanisms underlying the non-canonical glycolytic enzyme activities are still not comprehensive. This review summarizes the current findings on the mechanisms fundamental to the non-glycolytic actions of glycolytic enzymes and their intermediates in maintaining the tumor microenvironment.

Bariatric Surgery in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine condition in premenopausal women and is a common cause of anovulatory subfertility. Although obesity does not form part of the diagnostic criteria, it affects a significant proportion of women with PCOS and is strongly implicated in the pathophysiology of the disease. Both PCOS and obesity are known to impact fertility in women; obesity also reduces the success of assisted reproductive technology (ART). With or without pharmacotherapy, lifestyle intervention remains the first-line treatment in women with PCOS and obesity. Bariatric surgery is still an experimental treatment in women with PCOS and subfertility. This review will present an overview of the pathophysiology of PCOS and obesity and the role of bariatric surgery. Although data are sparse regarding the impact of bariatric surgery on subfertility in women with PCOS and obesity, existing studies point to a beneficial role in treating metabolic and reproductive dysfunction.

Association between residual islet beta-cell function and achieving the target of time in range in inpatients with type 2 diabetes undergoing antidiabetic treatment: An observation study

AIM

To assess whether the beta-cell function of inpatients undergoing antidiabetic treatment influences achieving time in range (TIR) and time above range (TAR) targets.

MATERIALS AND METHODS

This cross-sectional study included 180 inpatients with type 2 diabetes. TIR and TAR were assessed by a continuous glucose monitoring system, with target achievement defined as TIR more than 70% and TAR less than 25%. Beta-cell function was assessed by the insulin secretion-sensitivity index-2 (ISSI2).

RESULTS

Following antidiabetic treatment, logistic regression analysis showed that lower ISSI2 was associated with a decreased number of inpatients achieving TIR (OR = 3.10, 95% CI: 1.19-8.06) and TAR (OR = 3.40, 95% CI: 1.35-8.55) targets after adjusting for potential confounders. Similar associations still existed in those participants treated with insulin secretagogues (TIR: OR = 2.91, 95% CI: 0.90-9.36, P = .07; TAR, OR = 3.14, 95% CI: 1.01-9.80) or adequate insulin therapy (TIR: OR = 2.84, 95% CI: 0.91-8.81, P = .07; TAR, OR = 3.24, 95% CI: 1.08-9.67). Furthermore, receiver operating characteristic curves showed that the diagnostic value of the ISSI2 for achieving TIR and TAR targets was 0.73 (95% CI: 0.66-0.80) and 0.71 (95% CI: 0.63-0.79), respectively.

CONCLUSIONS

Beta-cell function was associated with achieving TIR and TAR targets. Stimulating insulin secretion or exogenous insulin treatment could not overcome the disadvantage of lower beta-cell function on glycaemic control.

Glucagon-like Peptide-1 Receptor Agonist Treatment With Semaglutide in Type 1 Diabetes

The efficacy of glucagon-like peptide-1 receptor agonists in type 2 diabetes is well established, but their role in type 1 diabetes (T1DM) is less clear. A 36-year-old woman with a 27-year history of T1DM and undetectable c-peptide presented for review of weight management, with body mass index 29.3 kg/m2. A previous trial of dapagliflozin led to no improvement in weight or glycemic control. Semaglutide was introduced (0.25 mg weekly increased to 0.5 mg weekly) and was well tolerated. After 6 months, weight had decreased by 16 kg and insulin dose by 36%. Despite less insulin, hemoglobin A1c improved, with reduced glycemic variability and no increase in hypoglycemia. Semaglutide may exert significant metabolic benefits in patients with established T1DM, even where c-peptide is no longer detectable. This case supports the need for a dedicated trial examining potential benefits of semaglutide in T1DM.

Comparing the effectiveness of continuous subcutaneous insulin infusion with multiple daily insulin injection for patients with type 1 diabetes mellitus evaluated by retrospective continuous glucose monitoring: A real-world data analysis

Objective

Regarding the effects and practical application of insulin pumps on patients with type 1 diabetes mellitus (T1DM), the real-world evidence is limited especially concerning the incidence of hypoglycemia. This study aimed to compare the efficacy of continuous subcutaneous insulin infusion (CSII) therapy with multiple daily injection (MDI) therapy on glycemic metrics evaluated by retrospective continuous glucose monitoring (CGM) in Chinese patients with T1DM.

Methods

In total, 362 T1DM Chinese patients from the outpatient department of the Second Xiangya Hospital, Central South University, who underwent intensive insulin therapy and used a retrospective CGM system were included in this retrospective cross-sectional study. Comprehensive analysis of clinical and biological features and retrospective CGM derived-metrics was performed on the 362 enrolled T1DM patients who underwent CSII (n = 61) or MDI (n = 301) therapy (defined as 4 or more insulin injections per day).

Results

Our findings demonstrated that patients who underwent CSII therapy, compared with those who received MDI therapy, had lower levels of hemoglobin A1c (HbA1c) and fasting blood glucose; moreover, CSII therapy was associated with better glycemic outcomes in terms of increasing time in range (TIR), decreasing time above range (TAR), and achieving CGM-associated targets of TIR ≥70% and TAR <25%. However, patients who underwent CSII therapy did not experience decreasing time below range (TBR), achieving CGM-associated targets of TBR <4%, and reduction of the risk of hypoglycemia as evidenced by comparing TBR and low blood glucose index (LBGI) between the two treatment regimens. The parameters of glycemic variability, such as standard deviation of glucose (SD), mean amplitude glycemic excursion (MAGE), and large amplitude glycemic excursion (LAGE) in T1DM patients who underwent CSII therapy outperformed.

Conclusion

Our results provided further evidence that CSII therapy is safe and effective for management of Chinese T1DM patients, which was confirmed by a lower HbA1c level and better CGM-derived metrics but no demonstration of improvment in the risk of hypoglycemia. To achieve more satisfactory glycemic outcomes through the utilization of CSII therapy for Chinese T1DM patients, a strong physician-patient relationship is essential.