Insulin Secretory Capacity Research Articles

Practice guideline: Statement regarding treatment for suspected slowly progressive type 1 diabetes (SPIDDM; probable) cases (English version)

AbstractInsulin treatment should be introduced in patients with slowly progressive type 1 diabetes (SPIDDM; definite), according to the revised diagnostic criteria of SPIDDM (2023). In contrast, SPIDDM (probable) patients are in a non‐insulin‐dependent state; therefore, a more flexible treatment can be considered, although sulfonylurea agents should be avoided. Insulin treatment has been shown to maintain endogenous insulin secretion capacity in SPIDDM (probable); however, this does not mean that all SPIDDM (probable) patients should use insulin from the early phase. Dipeptidyl peptidase‐4 inhibitors and biguanides might be the treatment of choice for SPIDDM (probable), but no evidence exists for other hypoglycemic agents. In any case, careful monitoring of the endogenous insulin secretion capacity should be carried out, and if a decrease in insulin secretion capacity is suspected, a change in treatment should be considered to prevent progression to an insulin‐dependent state.

Identifying and optimizing critical process parameters for large-scale manufacturing of iPSC derived insulin-producing β-cells

BackgroundType 1 diabetes, an autoimmune disorder leading to the destruction of pancreatic β-cells, requires lifelong insulin therapy. Islet transplantation offers a promising solution but faces challenges such as limited availability and the need for immunosuppression. Induced pluripotent stem cells (iPSCs) provide a potential alternative source of functional β-cells and have the capability for large-scale production. However, current differentiation protocols, predominantly conducted in hybrid or 2D settings, lack scalability and optimal conditions for suspension culture.MethodsWe examined a range of bioreactor scaleup process parameters and quality target product profiles that might affect the differentiation process. This investigation was conducted using an optimized High Dimensional Design of Experiments (HD-DoE) protocol designed for scalability and implemented in 0.5L (PBS-0.5 Mini) vertical wheel bioreactors.ResultsA three stage suspension manufacturing process is developed, transitioning from adherent to suspension culture, with TB2 media supporting iPSC growth during scaling. Stage-wise optimization approaches and extended differentiation times are used to enhance marker expression and maturation of iPSC-derived islet-like clusters. Continuous bioreactor runs were used to study nutrient and growth limitations and impact on differentiation. The continuous bioreactors were compared to a Control media change bioreactor showing metabolic shifts and a more β-cell-like differentiation profile. Cryopreserved aggregates harvested from the runs were recovered and showed maintenance of viability and insulin secretion capacity post-recovery, indicating their potential for storage and future transplantation therapies.ConclusionThis study demonstrated that stage time increase and limited media replenishing with lactate accumulation can increase the differentiation capacity of insulin producing cells cultured in a large-scale suspension environment.

Novel treatment options in patients with maturity onset diabetes of the young.

Maturity onset diabetes of the young (MODY) is the most common monogenetic form of diabetes with an autosomal dominant inheritance pattern. MODY is caused by mutations in genes that are important for the development and function of pancreatic beta cells, resulting in impaired insulin secretion capacity. To date, 14 different types have been described. While GCK-MODY (formerly MODY-2) generally requires no drug therapy, other forms of MODY such as HNF1A-MODY (formerly MODY-3) and HNF4A (formerly MODY-1) usually respond very well to sulfonylurea therapy. However, these MODY forms are characterised by a progressive course, meaning that insulin therapy is often required as the disease progresses. Both sulfonylurea therapy and insulin therapy are associated with an increased risk of hypoglycaemia and frequent weight gain. Newer blood glucose-lowering therapies, such as SGLT2 inhibitors (SGLT2i), DPP-4 inhibitors (DPP4i) and GLP-1 receptor agonists (GLP-1RA), have a much lower risk of hypoglycaemia and usually have a favourable effect on body weight. This review aims to provide an overview of the treatment of MODY patients with SGLT2i, DPP4i and GLP-1RA on the basis of previously published clinical studies, case series and case reports.

8283 Diabetes Mellitus in Patients with Hemochromatosis- A Diagnostic and Therapeutic Challenge

Abstract Disclosure: U. Rafat: None. M. Siddiqui: None. J.L. Gilden: Other; Self; Novartis Pharmaceuticals. A. Moid: Other; Self; Novartis Pharmaceuticals. Background: Primary Hemochromatosis is a genetic condition most commonly due to two sets of mutations in the Human homeostatic iron regular Protein (HFE) gene. HFE modulates the expression of hepcidin, which regulates intestinal iron absorption, plasma iron concentration and distribution of iron in tissues. Hemochromatosis patients are at high risk for developing diabetes mellitus (DM) due to iron overload in the pancreas with damage to Beta cells and impaired insulin secretory capacity. Hemochromatosis is often called Bronze Diabetes due to brown discoloration of the skin from accumulation of iron, and is characterized by hepatic fibrosis, fatigue, arthralgias, cirrhosis, DM, arthropathy, pigmentation and cardiomyopathy. Case: We present a Caucasian male with homozygous hereditary hemochromatosis, diagnosed by liver biopsy at age 40 due to transaminitis and Ferritin level of 1500 ng/mL and Genetic testing- 2 copies of HFE gene pathogenic variant (C282Y). He was later diagnosed with DM age 51, started on Metformin and referred to Endocrine clinic with abdominal bloating, and polyarticular arthralgias. Physical exam=Vital Signs normal (WT. 231lbs, BMI 34), with splenomegaly, but normal musculoskeletal exam and skin without bronze discoloration. Both parents had T2DM. Lab- Hb a1c 8.7% (0.0-5.6), Iron saturation 71% (10-50), Ferritin 66.3 ng/mL (26-388), C-Peptide 3.30 ng/ml (0.81-3.85), with glucose level of 119 mg/dL, and negative IA-2 <5.4 U/mL, negative Islet cell antibody, GAD 65 <5 IU/mL (nl <5), Insulin Autoantibody <0.4 U/mL (nl <0.4), and Zinc Transporter 8 antibodies <10 U/mL (nl <15). Liver tests- AST 39 U/L(10-37), ALT 77 U/L (10-65), ALP 89 U/L (45-117), total bilirubin 1.1 mg/dL(0.2-1.2). Hormonal evaluation included TSH 1.2 uIU/mL (0.55-4.78), ACTH 19 pg/mL (0-47), AM Cortisol 16.28 ug/d (5.30-22.50) IGF1 158 ng/mL (50-317) FSH 9.6 mIU/mL(l.40-18.10), LH 5.09 mIU/mL (1.50-9.30), Prolactin 7.40 ng/mL(2.10-17.70), total testosterone 374 ng/dL(250-1100), free testosterone 66.2 pg/mL (35.0-155.0). Echocardiogram-left ventricular hypertrophy and thick right ventricular wall with concerns for iron overload. Hba1c improved to 6.6% on Metformin. Fructosamine 351umol/L (151-300). In the absence of advanced cardiac, hepatic and other organ involvement, and presence of elevated C-peptide and high BMI, this patient is being managed as T2DM, with low threshold to initiate insulin therapy considering possibility of concomitant Bronze DM. Conclusion: It is important to determine type of DM, so appropriate management options can be devised. While insulin is recommended for management in Bronze Diabetes, insulin sensitizers, such as metformin and/or GLP 1 agonists can be used in type 2 DM. One must also consider therapy based upon the risk of cancer and acute pancreatitis in the setting of pancreatic iron overload, when considering antihyperglycemic therapies. Presentation: 6/2/2024

6905 The Necessity For New Criteria To Evaluate Overbasalization In East Asian Patients With Type 2 Diabetes Using Basal Insulin

Abstract Disclosure: H. Jang: None. Background: Overbasalization, which refers to adjusting the dose of basal insulin beyond an appropriate dose, should be avoided when using basal insulin in patients with type 2 diabetes. It is recommended to evaluate overbasalization when the basal insulin dose exceeds 0.5 units/kg/day or when post-meal glucose levels are > 180 mg/dL. However, this is an expert opinion, and specific criteria for East Asians have not been presented. Methods: Patients with type 2 diabetes using basal insulin (insulin glargine U-100, insulin glargine U-300, insulin degludec, NPH) at Seoul National University Bundang hospital from December 2020 to November 2023, with fasting plasma glucose (FPG) levels between 80 mg/dL and 130 mg/dL, were retrospectively analyzed. Patients with CKD ≤ grade 3b (estimated glomerular filtration rate < 45 mL/min/1.73m2), those taking medications such as steroids that may affect blood glucose levels, and patients undergoing cancer treatment were excluded. Results: A total of 548 patients were analyzed. The mean age of the subjects was 64.7 ± 12.4 years, with 299 (54.6%) being male, and the mean body mass index was 25.1 ± 6.6 kg/m2. The mean duration of diabetes was 18.1 ± 9.6 years. The mean HbA1c level was 7.7 ± 1.1%, while the mean fasting plasma glucose and median fasting C-peptide levels were 105.4 ± 13.9 mg/dL and 1.4 [0.8, 2.1] ng/mL, respectively. Insulin degludec being the most commonly administered (279 [50.9%]). The mean 2-hr postprandial glucose was 206.3 ± 64.8 mg/dL, with 350 (63.9%) having 2-hr postprandial glucose > 180 mg/dL. The administered insulin dose was 0.35 ± 0.17 units/kg/day, and 101 (18.4%) had an insulin dose > 0.5 units/kg/day. Conclusion: In East Asian patients with type 2 diabetes receiving basal insulin, although high 2-hr postprandial glucose levels suggest the possibility of overbasalization, the administered dosage of basal insulin was relatively low. Considering the lower insulin secretion capacity in East Asians, it is thought that new, specific criteria for overbasalization in East Asians are necessary. Presentation: 6/3/2024

Nicotinamide Mononucleotide (NMN) Ameliorates Free Fatty Acid-Induced Pancreatic β-Cell Dysfunction via the NAD+/AMPK/SIRT1/HIF-1α Pathway.

As the sole producers of insulin under physiological conditions, the normal functioning of pancreatic β cells is crucial for maintaining glucose homeostasis in the body. Due to the high oxygen and energy demands required for insulin secretion, hypoxia has been shown to play a critical role in pancreatic β-cell dysfunction. Lipid metabolism abnormalities, a common metabolic feature in type 2 diabetic patients, are often accompanied by tissue hypoxia caused by metabolic overload and lead to increased free fatty acid (FFA) levels. However, the specific mechanisms underlying FFA-induced β-cell dysfunction remain unclear. Nicotinamide mononucleotide (NMN), a naturally occurring bioactive nucleotide, has garnered significant attention in recent years for its effectiveness in replenishing NAD+ and alleviating various diseases. Nevertheless, studies exploring the mechanisms through which NMN influences β-cell dysfunction remain scarce. In this study, we established an in vitro β-cell dysfunction model by treating INS-1 cells with palmitate (PA), including control, PA-treated, and PA combined with NMN or activator/inhibitor groups. Compared to the control group, cells treated with PA alone showed significantly reduced insulin secretion capacity and decreased expression of proteins related to the NAD+/AMPK/SIRT1/HIF-1α pathway. In contrast, NMN supplementation significantly restored the expression of pathway-related proteins by activating NAD+ and effectively improved insulin secretion. Results obtained using HIF-1α and AMPK inhibitors/activators further supported these findings. In conclusion, our study demonstrates that NMN reversed the PA-induced downregulation of the NAD+/AMPK/SIRT1/HIF-1α pathway, thereby alleviating β-cell dysfunction. Our study investigated the mechanisms underlying PA-induced β-cell dysfunction, examined how NMN mitigates this dysfunction and offered new insights into the therapeutic potential of NMN for treating β-cell dysfunction and T2DM.

Beta cell specific ZnT8 gene deficiency and resulting loss in zinc content significantly improve insulin secretion

Zinc transporter 8 (ZnT8) is highly expressed in pancreatic beta cells, localizes to insulin secretory granules (ISG), and regulates zinc content. ZnT8 gene polymorphisms have revealed a relationship between ZnT8 activity and type 2 diabetes (T2D) risk, however, the role of beta-cell ZnT8 is not well understood.A beta cell specific ZnT8 knockout (ZnT8 BKO) mouse model was investigated. ZnT8 BKO islets showed significantly reduced ZnT8 gene expression and reduced zinc content. Compared to controls, ZnT8 BKO mice displayed significantly elevated plasma insulin levels and improved glucose tolerance following acute insulin resistance induced via S961. Glucose stimulated insulin secretion from isolated ZnT8 BKO pancreatic islets revealed enhanced insulin secretion capacity. The difference in insulin secretion between ZnT8 BKO and control islets was negated upon zinc supplementation, and the inhibitory effect of zinc on insulin secretion was confirmed in human islets.These results indicate that the loss of ZnT8 activity and accompanying reduced cellular zinc are associated with increased insulin secretion capacity. The reduction in secreted insulin content upon zinc supplementation in ZnT8 BKO islets suggests that ISG-released zinc normally tempers insulin secretion.

Glucagon Stimulation Test and Insulin Secretory Capacity in Clinical Assessment of Incretin-Based Therapy for Diabetes.

Evaluation of insulin secretory capacity is essential to understand the pathophysiological condition of individuals with diabetes and to assess the efficacy of drugs used in treatment of the disease. The 1 mg intravenous glucagon stimulation test (GST) is widely used to evaluate residual β cell function; we previously reported that GST assessment of insulin secretory capacity is useful in assessing the efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RAs). However, recent reports indicate that pharmacological concentrations of glucagon stimulate insulin secretion through GLP-1 receptors, confounding the issue. The present studies were undertaken to reassess the reliability of the GST for evaluation of insulin secretory capacity under GLP-1RAs and dipeptidyl peptidase-4 inhibitors (DPP-4is). Our first study comprised individuals initiated with the treatment of GLP-1RAs evaluated by GSTs before and after treatment. Although the fasting C-peptide levels (CPR) were elevated after treatment, the induction of insulin secretion by glucagon was significantly reduced. Our second study compared glucagon-induced insulin secretion between DPP-4i users and non-users, assessed by GST after propensity score matching. While the fasting CPR were similar in the two investigations, glucagon-induced insulin secretion was significantly lower with DPP-4i use. These results suggest that GST might underestimate insulin secretory capacity under incretin-based therapy.

Global deletion of G protein-coupled receptor 55 impairs glucose homeostasis during obesity by reducing insulin secretion and β-cell turnover.

To investigate the effect of G protein-coupled receptor 55 (GPR55) deletion on glucose homeostasis and islet function following diet-induced obesity. GPR55-/- and wild-type (WT) mice were fed ad libitum either standard chow (SC) or a high-fat diet (HFD) for 20 weeks. Glucose and insulin tolerance tests were performed at 9/10 and 19/20 weeks of dietary intervention. Insulin secretion in vivo and dynamic insulin secretion following perifusion of isolated islets were also determined, as were islet caspase-3/7 activities and β-cell 5-bromo-20-deoxyuridine (BrdU) incorporation. GPR55-/- mice fed a HFD were more susceptible to diet-induced obesity and were more glucose intolerant and insulin resistant than WT mice maintained on a HFD. Islets isolated from HFD-fed GPR55-/- mice showed impaired glucose- and pcacahorbol 12-myristate 13-acetate-stimulated insulin secretion, and they also displayed increased cytokine-induced apoptosis. While there was a 5.6 ± 1.6-fold increase in β-cell BrdU incorporation in the pancreases of WT mice fed a HFD, this compensatory increase in β-cell proliferation in response to the HFD was attenuated in GPR55-/- mice. Under conditions of diet-induced obesity, GPR55-/- mice show impaired glucose handling, which is associated with reduced insulin secretory capacity, increased islet cell apoptosis and insufficient compensatory increases in β-cell proliferation. These observations support that GPR55 plays an important role in positively regulating islet function.

Islet transplantation in Korea.

Type 1 diabetes mellitus is characterized by absolute insulin deficiency, which requires life-long insulin replacement. Exogenous multiple-daily insulin injections are most commonly prescribed for patients with type 1 diabetes mellitus. However, exogenous insulin supply often fails to cope with real-time changing life-log variables, such as activity, diet and stress, which results in recurrent hypo- and hyperglycemia in patients with type 1 diabetes mellitus. Islet transplantation is an ideal method to treat patients with type 1 diabetes mellitus, as it can restore the endogenous capacity of glucose-stimulated insulin secretion. However, due to donor scarcity and technical barriers, only a limited number of islet transplantations have been carried out in Asia, including South Korea. Since 2013, our center has carried out two allogenic islet transplantations, with one case leading to near total insulin independence after one-to-one islet transplantation. Although the other patient failed to restore endogenous insulin production, there was a remarkable improvement in hypoglycemia. We speculate that islet transplantation remains an important and ideal treatment option for patients with type 1 diabetes mellitus who suffer from recurrent severe hypoglycemia.

Diabetic Ketoacidosis in Patients with Maturity-Onset Diabetes of the Young.

Maturity-onset diabetes of the young (MODY) is the most frequent monogenetic diabetes form. It is caused by mutations in genes important for the development and function of pancreatic beta-cells, resulting in impaired insulin secretion capacity. Up to now, 14 different types have been described. The inheritance pattern is autosomal dominant, leading to a strong family history with more than three affected generations. Young age at diagnosis and lack of pancreatic autoantibodies are further characteristics of MODY. The presence of diabetic ketoacidosis (DKA) was long regarded as an exclusion criterion for MODY. However, in recent years, several case reports on MODY patients presenting with DKA have been published. The present study aimed to give an overview of the current knowledge of DKA in MODY patients, with a collection of published case studies as a prerequisite for this review.

Association of xanthine oxidoreductase inhibitor use with insulin secretory capacity in patients with type 2 diabetes.

Xanthine oxidoreductase (XOR) inhibitor treatment, which reduces reactive oxygen species (ROS) production and increases adenosine triphosphate (ATP) synthesis, has been reported to improve glycemic control. The possible protective effects of XOR inhibitor treatment on insulin secretory capacity were investigated in patients with type 2 diabetes. This retrospective cross-sectional study included 428 patients with type 2 diabetes. Insulin secretory capacity was assessed based on fasting serum C-peptide concentration (CPR) and C-peptide index (CPI) in all subjects, while insulin resistance in non-insulin users (n = 312) was determined using the homeostasis model assessment of insulin resistance (HOMA-IR) index. Median values for CPR and CPI in all subjects were 2.4 ng/mL and 1.5, respectively, while that for HOMA-IR in non-insulin users was 3.2. The XOR inhibitor users (n = 72) had significantly (P < 0.001) higher CPR and CPI levels than non-users (n = 356). Multivariable regression analyses showed XOR inhibitor use was positively associated with CPR (β = 0.153, P = 0.001) and CPI (β = 0.144, P = 0.001). Similar results were observed in propensity score analyses. In subgroup analyses of patients with a preserved estimated glomerular filtration rate (≥60 mL/min/1.73 m2) and non-insulin users, these associations remained significant. Furthermore, the associations were significant in patients with lower (≤6.0 mg/dL) but not with higher (>6.0 mg/dL) uric acid levels (P for interaction <0.05). On the other hand, XOR inhibitor use showed no significant association with HOMA-IR. The results of XOR inhibitor treatment, especially a sufficient reduction in serum uric acid level, may provide protective effects on insulin secretory capacity in patients with type 2 diabetes.

High glutamic acid decarboxylase antibody titers may be associated with a decline in β-cell function over time and future insulin deficiency in latent autoimmune diabetes in adults

AimsLatent autoimmune diabetes in adults (LADA) is characterized by positive islet-associated autoantibodies including glutamic acid decarboxylase antibody (GADA), and gradual decline in insulin secretion, progressing to insulin dependency. This cross-sectional study aimed to determine whether GADA by enzyme-linked immunosorbent assay (GADA-ELISA) titer of ≥180 U/mL could be associated with decline in β-cell function in participants with LADA. MethodsSixty-three participants with LADA were recruited and an association between insulin secretion capacity and disease duration was investigated. Insulin peptide-specific inflammatory immunoreactivity was investigated to determine the disease’s activity. ResultsThere was a significant inverse correlation between disease duration and C-peptide index in participants with GADA-ELISA titer of ≥180 U/mL (Spearman’s r (rs) = –0.516, p < 0.01). The positivity rate of insulin peptide-specific inflammatory immunoreactivity was significantly higher in those with ≥180 U/mL than in those with <180 U/mL (p < 0.05). In participants with human leukocyte antigen (HLA)-DRB1*04:05, a significant inverse correlation was observed between disease duration and C-peptide index in those with ≥180 U/mL (rs = −0.751, p < 0.01). ConclusionsGADA-ELISA titer of ≥180 U/mL, especially with HLA-DRB1*04:05, might reflect higher disease activity and may be associated with decline in β-cell function over time and future insulin dependency in LADA.

Obesity-induced upregulation of miR-483-5p impairs the function and identity of pancreatic β-cells.

To assess the expression and function of miR-483-5p in diabetic β cells. The expression of miR-483-5p was evaluated in the pancreatic islets of obesity mouse models by quantitative reverse transcription polymerase chain reaction. Dual-luciferase activity, and western blotting assays, were utilized for miR-483-5p target gene verification. Mice with β cell-specific miR-483-5p downregulation were studied under metabolic stress (i.e. a high-fat diet) condition. Lineage tracing was used to determine β-cell fate. miR-483-5p increased in the islets of obese mouse models. Expression levels of miR-483-5p were significantly upregulated with the treatment of high glucose and palmitate, in both MIN6 cells and mouse islets. Overexpression of miR-483-5p in β cells results in impaired insulin secretion and β-cell identity. Cell lineage-specific analyses revealed that miR-483-5p overexpression deactivated β-cell identity genes (insulin, Pdx1 and MafA) and derepressed β-cell dedifferentiation (Ngn3) genes. miR-483-5p downregulation in β cells of high-fat diet-fed mice alleviated diabetes and improved glucose intolerance by enhancing insulin secretory capacity. These detrimental effects of miR-483-5p relied on its seed sequence recognition and repressed expression of its target genes Pdx1 and MafA, two crucial markers of β-cell maturation. These findings indicate that the miR-483-5p-mediated reduction of mRNAs specifies β-cell identity as a contributor to β-cell dysfunction via the loss of cellular differentiation.

Efficacy and safety of oral semaglutide in older patients with type 2 diabetes: a retrospective observational study (the OTARU-SEMA study)

BackgroundOral semaglutide in older subjects with type 2 diabetes was as effective as in younger subjects, according to phase 3 clinical trials. However, its efficacy can be limited in very aged population, due to the presence of impaired cognitive function and the complex instructions for its use. Here, we investigated its efficacy and safety by further age bracket in older subjects in real-world.MethodsWe retrospectively studied subjects > 65 years of age with type 2 diabetes who started oral semaglutide treatment. The primary outcome was the change in glycated hemoglobin (HbA1c) over 6 months. Adverse events and cognitive function were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE) and the Hasegawa Dementia Rating Scale-revised (HDS-R). The achievement rate of glycemic targets was evaluated based on the age, health status of subjects and their use of anti-diabetic agents which can cause hypoglycemia, with additional analysis between two subgroups; early (65–74) versus late (≥ 75) older. Furthermore, we evaluated the relationships between their improvements in HbA1c and the baseline characteristics of the subjects, including their cognitive function and insulin secretory capacity.ResultsWe studied the efficacy of the drug in 24 subjects. Their HbA1c and body weight significantly decreased (− 13.1 ± 7.5 mmol/mol and − 3.0 ± 2.4 kg, respectively; P < 0.01). Although cognitive function was lower in the late older group (r = −0.57, P < 0.01), changes in HbA1c showed no difference between the two subgroups (P = 0.66) and it correlated with the insulin secretory capacity rather than cognitive function (r = −0.49, P < 0.05). Glycemic targets were more likely to be achieved (P < 0.01), but HbA1c excessively decreased in late older subjects who were also using insulin or an insulin secretagogue. The frequency of adverse events was similar to that in the clinical trial, whereas discontinuation of medication were more frequent among the late older subjects (Early; n = 2, Late; n = 4).ConclusionsOral semaglutide improves the glycemic control of older subjects, but it might be a risk for potential hypoglycemia and discontinuation because of adverse events in subjects of ≥ 75 years. Attention should be paid to insulin secretory capacity and concomitant medications rather than concern about adherence.

Decreased β-cell volume and insulin secretion but preserved glucose tolerance in a growth hormone insensitive pig model

PurposeGrowth hormone (GH) is a central regulator of β-cell proliferation, insulin secretion and sensitivity. Aim of this study was to investigate the effect of GH insensitivity on pancreatic β-cell histomorphology and consequences for metabolism in vivo.MethodsPancreata from pigs with growth hormone receptor deficiency (GHR-KO, n = 12) were analyzed by unbiased quantitative stereology in comparison to wild-type controls (WT, n = 12) at 3 and 7–8.5 months of age. In vivo secretion capacity for insulin and glucose tolerance were assessed by intravenous glucose tolerance tests (ivGTTs) in GHR-KO (n = 3) and WT (n = 3) pigs of the respective age groups.ResultsUnbiased quantitative stereological analyses revealed a significant reduction in total β-cell volume (83% and 73% reduction in young and adult GHR-KO vs. age-matched WT pigs; p < 0.0001) and volume density of β-cells in the pancreas of GHR-KO pigs (42% and 39% reduction in young and adult GHR-KO pigs; p = 0.0018). GHR-KO pigs displayed a significant, age-dependent increase in the proportion of isolated β-cells in the pancreas (28% in young and 97% in adult GHR-KO vs. age-matched WT pigs; p = 0.0009). Despite reduced insulin secretion in ivGTTs, GHR-KO pigs maintained normal glucose tolerance.ConclusionGH insensitivity in GHR-KO pigs leads to decreased β-cell volume and volume proportion of β-cells in the pancreas, causing a reduced insulin secretion capacity. The increased proportion of isolated β-cells in the pancreas of GHR-KO pigs highlights the dependency on GH stimulation for proper β-cell maturation. Preserved glucose tolerance accomplished with decreased insulin secretion indicates enhanced sensitivity for insulin in GH insensitivity.

Postpartum development of metabolic dysfunction-associated steatotic liver disease in a lean mouse model of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is associated with increased postpartum risk for metabolic dysfunction-associated steatotic liver disease (MASLD). GDM-related MASLD predisposes to advanced liver disease, necessitating a better understanding of its development in GDM. This preclinical study evaluated the MASLD development in a lean GDM mouse model with impaired insulin secretion capacity. Lean GDM was induced by short-term 60% high-fat diet and low-dose streptozotocin injections (60 mg/kg for 3 days) before mating in C57BL/6N mice. The control dams received only high-fat diet or low-fat diet. Glucose homeostasis was assessed during pregnancy and postpartum, whereas MASLD was assessed on postpartum day 30 (PP30). GDM dams exhibited a transient hyperglycemic phenotype during pregnancy, with hyperglycaemia reappearing after lactation. Lower insulin levels and impaired glucose-induced insulin response were observed in GDM mice during pregnancy and postpartum. At PP30, GDM dams displayed higher hepatic triglyceride content compared controls, along with increased MAS (MASLD) activity scores, indicating lipid accumulation, inflammation, and cell turnover indices. Additionally, at PP30, GDM dams showed elevated plasma liver injury markers. Given the absence of obesity in this double-hit GDM model, the results clearly indicate that impaired insulin secretion driven pregnancy hyperglycaemia has a distinct contribution to the development of postpartum MASLD.

The enduring metabolic improvement of combining dual amylin and calcitonin receptor agonist and semaglutide treatments in a rat model of obesity and diabetes.

Long-acting dual amylin and calcitonin receptor agonists (DACRAs) are novel candidates for the treatment of type 2 diabetes and obesity due to their beneficial effects on body weight, glucose control, and insulin action. However, how the metabolic benefits are maintained after long-lasting treatment is unknown. This study investigates the long-term anti-obesity and anti-diabetic treatment efficacy of the DACRA KBP-336 alone and combined with the GLP-1 analog semaglutide. Zucker diabetic Sprague Dawley (ZDSD) rats with obesity and diabetes received KBP-336 (4.5 nmol/kg Q3D), semaglutide (50 nmol/kg Q3D), or the combination for 7 mo, and the treatment impact on body weight, food intake, glucose control, and insulin action was evaluated. Furthermore, serum levels of the cardiac fibrosis biomarker endotrophin were evaluated. KBP-336, semaglutide, and the combination lowered body weight significantly compared with the vehicle, with the combination inducing a larger and more sustained weight loss than either monotherapy. All treatments resulted in reduced fasting blood glucose levels and HbA1c levels and improved glucose tolerance compared with vehicle-treated rats. Furthermore, all treatments protected against lost insulin secretory capacity and improved insulin action. Serum levels of endotrophin were significantly lowered by KBP-336 compared with vehicle. This study shows the benefit of combining KBP-336 and semaglutide to obtain significant and sustained weight loss, as well as improved glucose control. Furthermore, KBP-336-driven reductions in circulating endotrophin indicate a clear reduction in the risk of complications. Altogether, KBP-336 is a promising candidate for the treatment of obesity and type 2 diabetes both alone and in combination with GLP-1 analogs.NEW & NOTEWORTHY These studies describe the benefit of combining dual amylin and calcitonin receptor agonists (DACRA) with semaglutide for long-term treatment of obesity and type 2 diabetes. Combination treatment induced sustained weight loss and improved glucose control. A DACRA-driven reduction in a serological biomarker of cardiac fibrosis indicated a reduced risk of complications. These results highlight DACRAs as a promising candidate for combination treatment of obesity and type 2 diabetes and related long-term complications.

Dapagliflozin administration to a mouse model of type 2 diabetes induces DNA methylation and gene expression changes in pancreatic islets

Decreased pancreatic β-cell volume is a serious problem in patients with type 2 diabetes mellitus, and there is a need to establish appropriate treatments. Increasingly, sodium/glucose cotransporter 2 (SGLT2) inhibitors, which have a protective effect on pancreatic β-cells, are being prescribed to treat diabetes; however, the underlying mechanism is not well understood. We previously administered SGLT2 inhibitor dapagliflozin to a mouse model of type 2 diabetes and found significant changes in gene expression in the early-treated group, which led us to hypothesize that epigenetic regulation was a possible mechanism of these changes. Therefore, we performed comprehensive DNA methylation analysis by methylated DNA immunoprecipitation using isolated pancreatic islets after dapagliflozin administration to diabetic model mice. As a result, we identified 31 genes with changes in expression due to DNA methylation changes. Upon immunostaining, cystic fibrosis transmembrane conductance regulator and cadherin 24 were found to be upregulated in islets in the dapagliflozin-treated group. These molecules may contribute to the maintenance of islet morphology and insulin secretory capacity, suggesting that SGLT2 inhibitors’ protective effect on pancreatic β-cells is accompanied by DNA methylation changes, and that the effect is long-term and not temporary. In future diabetes care, SGLT2 inhibitors may be expected to have positive therapeutic effects, including pancreatic β-cell protection.

Associations between time in range and insulin secretory capacity in Japanese patients with type 2 diabetes

Impaired insulin secretory capacity is associated with high glycemic variability in patients with type 2 diabetes (T2DM). However, there are no existing reports on the association between insulin secretory capacity and time in range (TIR). This retrospective study involved 330 T2DM admitted for diabetes education who underwent intermittently scanned continuous glucose monitoring (isCGM) and had their fasting serum C-peptide immunoreactivity (S-CPR) measured within 5 days of admission. The baseline characteristics were as follows: age, 60.2 years; glycated hemoglobin (HbA1c), 9.2%; S-CPR, 2.2 ng/mL; S-CPR index (S-CPR [ng/mL]/fasting plasma glucose [mg/dL] × 100), 1.6; and TIR, 60.3%. TIR correlated significantly with the S-CPR index, which was confirmed by multivariate analysis that included various factors such as HbA1c. Receiver operating characteristic (ROC) analysis showed that 1.88 was the optimal S-CPR index level to predict TIR ≥ 70%. In addition to HbA1c and biguanide use, the S-CPR index was a significant factor associated with TIR > 70%. S-CPR index values of ≥ 1.88 also correlated significantly with TIR > 70%. In conclusion, insulin secretory capacity is associated with TIR in Japanese T2DM, suggesting that the S-CPR index might be a potentially useful biomarker insulin secretory capacity, in association with TIR.Trial registration UMIN0000254333.