Notch1 Has an Important Role in β-Cell Mass Determination and Development of Diabetes

BackgroundNotch signaling pathway plays an important role in regulating pancreatic endocrine and exocrine cell fate during pancreas development. Notch signaling is also expressed in adult pancreas. There are few studies on the effect of Notch on adult pancreas. Here, we investigated the role of Notch in islet mass and glucose homeostasis in adult pancreas using Notch1 antisense transgenic (NAS).MethodsWestern blot analysis was performed for the liver of 8-week-old male NAS mice. We also conducted an intraperitoneal glucose tolerance test (IPGTT) and intraperitoneal insulin tolerance test in 8-week-old male NAS mice and male C57BL/6 mice (control). Morphologic observation of pancreatic islet and β-cell was conducted in two groups. Insulin secretion capacity in islets was measured by glucose-stimulated insulin secretion (GSIS) and perifusion.ResultsNAS mice showed higher glucose levels and lower insulin secretion in IPGTT than the control mice. There was no significant difference in insulin resistance. Total islet and β-cell masses were decreased in NAS mice. The number of large islets (≥250 µm) decreased while that of small islets (ConclusionOur study provides that Notch1 inhibition decreased insulin secretion and decreased islet and β-cell masses. It is thought that Notch1 inhibition suppresses islet proliferation and induces differentiation of small islets. In conclusion, Notch signaling pathway may play an important role in β-cell mass determination and diabetes.

Diagnosis and Treatment of Growth Hormone Deficiency: A Position Statement from Korean Endocrine Society and Korean Society of Pediatric Endocrinology

Growth hormone (GH) deficiency is caused by congenital or acquired causes and occurs in childhood or adulthood. GH replacement therapy brings benefits to body composition, exercise capacity, skeletal health, cardiovascular outcomes, and quality of life. Before initiating GH replacement, GH deficiency should be confirmed through proper stimulation tests, and in cases with proven genetic causes or structural lesions, repeated GH stimulation testing is not necessary. The dosing regimen of GH replacement therapy should be individualized, with the goal of minimizing side effects and maximizing clinical improvements. The Korean Endocrine Society and the Korean Society of Pediatric Endocrinology have developed a position statement on the diagnosis and treatment of GH deficiency. This position statement is based on a systematic review of evidence and expert opinions.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement

The Korean Endocrine Society (KES) published clinical practice guidelines for the treatment of acromegaly in 2011. Since then, the number of acromegaly cases, publications on studies addressing medical treatment of acromegaly, and demands for improvements in insurance coverage have been dramatically increasing. In 2017, the KES Committee of Health Insurance decided to publish a position statement regarding the use of somatostatin analogues in acromegaly. Accordingly, consensus opinions for the position statement were collected after intensive review of the relevant literature and discussions among experts affiliated with the KES, and the Korean Neuroendocrine Study Group. This position statement includes the characteristics, indications, dose, interval (including extended dose interval in case of lanreotide autogel), switching and preoperative use of somatostatin analogues in medical treatment of acromegaly. The recommended approach is based on the expert opinions in case of insufficient clinical evidence, and where discrepancies among the expert opinions were found, the experts voted to determine the recommended approach.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement / 대한내과학회지

Acromegaly is a chronic disorder caused by excessive growth hormone (GH) secretion. In most cases, the excess GH originates from GH-producing pituitary adenomas. Surgery is the preferred first-line treatment for patients with acromegaly, but medical management is considered when the disease persists after surgery or in cases where patients refuse surgery or are poor candidates for surgery. Somatostatin analogues are commonly used to treat acromegaly. The Korean Endocrine Society and the Korean Neuroendocrine Study Group have developed a position statement for the use of somatostatin analogues in the medical treatment of acromegaly. This position statement is based on evidence from the current literature and expert opinions. In the case of discrepancies among expert opinions, the experts voted to determine the recommended approach.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement / 대한내과학회지

Acromegaly is a chronic disorder caused by excessive growth hormone (GH) secretion. In most cases, the excess GH originates from GH-producing pituitary adenomas. Surgery is the preferred first-line treatment for patients with acromegaly, but medical management is considered when the disease persists after surgery or in cases where patients refuse surgery or are poor candidates for surgery. Somatostatin analogues are commonly used to treat acromegaly. The Korean Endocrine Society and the Korean Neuroendocrine Study Group have developed a position statement for the use of somatostatin analogues in the medical treatment of acromegaly. This position statement is based on evidence from the current literature and expert opinions. In the case of discrepancies among expert opinions, the experts voted to determine the recommended approach.

Autoimmune Encephalitis Associated with Thymoma

No abstract available.

The Well-Being and Treatment Satisfaction of Diabetic Patients in an Outpatient Setting at a General Hospital in Korea / 임상당뇨병

BACKGROUND: The aim of this study was to assess the psychological well-being and treatment satisfaction in patients with type 2 diabetes mellitus in a general hospital in Korea. METHODS: This study included 440 type 2 diabetes patients above 20 years of age. Well-Being Questionnaire-12 (WBQ-12) and Diabetes Treatment Satisfaction Questionnaire were used to survey well-being and treatment satisfaction, respectively. WBQ-12 consists of 4 categories: negative well-being (NWB), energy (ENE), positive well-being (PWB), and general well-being (GWB). RESULTS: There were significant associations between NWB scores and women, low education, low-income, and number of hospital admissions. Significant associations were also identified between ENE scores and men, higher education, insulin nonusers, high-income, compliance with recommended exercise, number of medications, satisfaction with treatment time, and poor glycemic control. PWB scores were significantly associated with high-income, satisfaction with waiting and treatment times, compliance with recommended diet and exercise, and number of medications. GWB scores were significantly associated with men, higher education, high-income, satisfaction with waiting and treatment times, compliance with recommended exercise, and number of medications. Treatment satisfaction was significantly associated with age, satisfaction with waiting and treatment times, compliance with recommended diet and exercise, and duration of diabetes. CONCLUSION: Diabetes care requires psychosocial support in addition to medical care. Unlike Western studies, our study found that satisfaction with waiting and treatment times had a strong correlation with well-being and treatment satisfaction in diabetes patients.

Effects of Short-Term Exenatide Treatment on Regional Fat Distribution, Glycated Hemoglobin Levels, and Aortic Pulse Wave Velocity of Obese Type 2 Diabetes Mellitus Patients

BACKGROUND: Most type 2 diabetes mellitus patients are obese and have obesity related vascular complications. Exenatide treatment is well known for both decreasing glycated hemoglobin levels and reduction in body weight. So, this study aimed to determine the effects of exenatide on body composition, glycated hemoglobin levels, and vascular stiffness in obese type 2 diabetes mellitus patients. METHODS: For 1 month, 32 obese type 2 diabetes mellitus patients were administered 5 µg of exenatide twice daily. The dosage was then increased to 10 µg. Patients' height, body weight, glycated hemoglobin levels, lipid profile, pulse wave velocity (PWV), body mass index, fat mass, and muscle mass were measured by using Inbody at baseline and after 3 months of treatment. RESULTS: After 3 months of treatment, glycated hemoglobin levels decreased significantly (P=0.007). Triglyceride, total cholesterol, and low density lipoprotein levels decreased, while aspartate aminotransferase and alanine aminotransferase levels were no change. Body weight, and fat mass decreased significantly (P=0.002 and P=0.001, respectively), while interestingly, muscle mass did not decrease (P=0.289). In addition to, Waist-to-hip ratio and aortic PWV decreased significantly (P=0.006 and P=0.001, respectively). CONCLUSION: Effects of short term exenatide use in obese type 2 diabetes mellitus with cardiometabolic high risk patients not only reduced body weight without muscle mass loss, body fat mass, and glycated hemoglobin levels but also improved aortic PWV in accordance with waist to hip ratio.

Clinical Guidelines for the Diagnosis and Treatment of Cushing's Disease in Korea

Cushing's disease (CD) is a rare disorder characterized by the overproduction of adrenocorticotropic hormone due to a pituitary adenoma that ultimately stimulates excessive cortisol secretion from the adrenal glands. Prior to the detection of pituitary adenomas, various clinical signs of CD such as central obesity, moon face, hirsutism, and facial plethora are usually already present. Uncontrolled hypercortisolism is associated with metabolic, cardiovascular, and psychological disorders that result in increased mortality. Hence, the early detection and treatment of CD are not only important but mandatory. Because its clinical manifestations vary from patient to patient and are common in other obesity-related conditions, the precise diagnosis of CD can be problematic. Thus, the present set of guidelines was compiled by Korean experts in this field to assist clinicians with the screening, diagnoses, and treatment of patients with CD using currently available tests and treatment modalities.

The Role of Glucagon-Like Peptide-1 Receptor Agonists in Type 2 Diabetes: Understanding How Data Can Inform Clinical Practice in Korea

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) reduce glycosylated hemoglobin (HbA1c, 0.5% to 1.0%), and are associated with moderate weight loss and a relatively low risk of hypoglycemia. There are differences between Asian and non-Asian populations. We reviewed available data on GLP-1RAs, focusing on Korean patients, to better understand their risk/benefit profile and help inform local clinical practice. Control of postprandial hyperglycemia is important in Asians in whom the prevalence of post-challenge hyperglycemia is higher (vs. non-Asians). The weight lowering effects of GLP-1RAs are becoming more salient as the prevalence of overweight and obesity among Korean patients increases. The higher rate of gastrointestinal adverse events amongst Asian patients in clinical trials may be caused by higher drug exposure due to the lower body mass index of the participants (vs. non-Asian studies). Data on the durability of weight loss, clinically important health outcomes, safety and optimal dosing in Korean patients are lacking. Use of GLP-1RAs is appropriate in several patient groups, including patients whose HbA1c is uncontrolled, especially if this is due to postprandial glucose excursions and patients who are overweight or obese due to dietary problems (e.g., appetite control). The potential for gastrointestinal adverse events should be explained to patients at treatment initiation to facilitate the promotion of better compliance.

A Case of Pneumatosis Cystoides Intestinalis and Portal Venous Gas Accompanied by Emphysematous Pyelonephritis in Type 2 Diabetes Mellitus / 임상당뇨병

Diabetes mellitus is a major risk factor for urinary tract infection (UTI); emphysematous pyelonephritis (EP), a complication of UTIs, often occurs in patients with underlying, poorly controlled diabetes mellitus. We report the case of an 87-year-old woman with EP in type 2 diabetes mellitus who developed pneumatosis cystoides intestinalis (PCI) with portal venous gas. PCI is a radiographic finding, which is found in a linear or cystic form of gas in the submucosa or subserosa of the bowel wall. PCI has two common presentations. Primary PCI is a benign idiopathic condition. Secondary PCI is associated with a wide variety of gastrointestinal and non-gastrointestinal diseases. PCI with portal venous gas in particular is associated with ischemic gastrointestinal disease. Initial pre-enhanced abdominopelvic computed tomography showed EP in the right kidney without PCI. Newly occurring PCI and hepatic portal venous gas were found in the right ascending colon after EP improved. This is a rare case of PCI accompanied by emphysematous pyelonephritis in type 2 diabetes mellitus. The patient's general condition improved with intravenous antibiotics and fluid therapy without a surgical approach. However, she was discharged without further treatment because the family refused any further evaluations and treatments.

Efficacy and Safety of Sustained-Release Recombinant Human Growth Hormone in Korean Adults with Growth Hormone Deficiency

PURPOSE: The administration of recombinant human growth hormone in adults with growth hormone deficiency has been known to improve metabolic impairment and quality of life. Patients, however, have to tolerate daily injections of growth hormone. The efficacy, safety, and compliance of weekly administered sustained-release recombinant human growth hormone (SR-rhGH, Declage(TM)) supplement in patients with growth hormone deficiency were evaluated. MATERIALS AND METHODS: This trial is 12-week prospective, single-arm, open-label trial. Men and women aged > or =20 years with diagnosed growth hormone deficiency (caused by pituitary tumor, trauma and other pituitary diseases) were eligible for this study. Each subject was given 2 mg (6 IU) of SR-rhGH once a week, subcutaneously for 12 weeks. Efficacy and safety at baseline and within 30 days after the 12th injection were assessed and compared. Score of Assessment of Growth Hormone Deficiency in Adults (AGHDA score) for quality of life and serum IGF-1 level. RESULTS: The IGF-1 level of 108.67+/-74.03 ng/mL was increased to 129.01+/-68.37 ng/mL (p=0.0111) and the AGHDA QoL score was decreased from 9.80+/-6.51 to 7.55+/-5.76 (p<0.0001) at week 12 compared with those at baseline. Adverse events included pain, swelling, erythema, and warmth sensation at the administration site, but many adverse events gradually disappeared during the investigation. CONCLUSION: Weekly administered SR-rhGH for 12 weeks effectively increased IGF-1 level and improved the quality of life in patients with GH deficiency without serious adverse events.

Glucagon-Like Peptide-1 (GLP-1) Agonist / 대한내과학회지

The prevalence of diabetes is increasing worldwide. Glycemic control has been shown to prevent microvascular complications. Many oral hyperglycemic drugs and insulin are being used in the treatment of diabetes, but the effects of those treatments are suboptimal. The two incretin hormones GLP-1 and GIP are released from L- and K-cells, respectively, in response to nutrient intake. GLP-1 stimulates glucose-dependent insulin release. Recently, incretin hormone-based therapies, including GLP-1 agonists and DPP-4 inhibitors, have been used as new treatment options to control glucose levels in patients with type 2 diabetes mellitus. The purpose of this article is to review the efficacy and safety of GLP-1 agonists in the treatment of type 2 diabetes.

Genetic Analysis of Multiple Endocrine Neoplasia Type 1 (MEN1) Leads to Misdiagnosis of an Extremely Rare Presentation of Intrasellar Cavernous Hemangioma as MEN1

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN1) is a rare inherited disorder characterized by the simultaneous occurrence of endocrine tumors in target tissues (mainly the pituitary, endocrine pancreas, and parathyroid glands). MEN1 is caused by mutations in the MEN1 gene, which functions as a tumor suppressor and consists of one untranslated exon and nine exons encoding the menin protein. This condition is usually suspected when we encounter patients diagnosed with tumors in multiple endocrine organs, as mentioned above. METHODS: A 65-year-old woman who underwent surgery for a pancreatic tumor (serous cystadenoma) 5 years previously was referred to our hospital due to neurologic symptoms of diplopia and left ptosis. Brain magnetic resonance imaging revealed a 3.4-cm lesion originating from the cavernous sinus wall and extending into the sellar region. It was thought to be a nonfunctioning tumor from the results of the combined pituitary function test. Incidentally, we found that she also had a pancreatic tumor, indicating the necessity of genetic analysis for MEN1. RESULTS: Genomic analysis using peripheral leukocytes revealed a heterozygous c.1621G>A mutation in the MEN1 gene that was previously reported to be either a pathogenic mutation or a simple polymorphism. We pursued a stereotactic approach to the pituitary lesion, and microscopic findings of the tumor revealed it to be an intrasellar cavernous hemangioma, a rare finding in the sellar region and even rarer in relation to oculomotor palsy. The patient recovered well from surgery, but refused further evaluation for the pancreatic lesion. CONCLUSION: There is great emphasis placed on genetic testing in the diagnosis of MEN1, but herein we report a case where it did not assist in diagnosis, hence, further discussion on the role of genetic testing in this disease is needed. Also, in cases of pituitary tumor with cranial nerve palsy, despite its low prevalence, intrasellar cavernous hemangioma could be suspected.

Hypothalamic Hypopituitarism Caused by Pituitary Stalk Dysgenesis / 대한내과학회지

Functional defects of the pituitary gland are a rare cause of pubertal delay. The pituitary stalk is an important structure that connects the hypothalamus and pituitary gland. A defect in fusion of the pituitary stalk and anterior pituitary gland will block the function of the anterior pituitary gland. A 28-year-old man was referred to our clinic with poorly developed secondary sexual characteristics. He had undeveloped facial, axillary, and pubic hair and was Tanner stage I. Laboratory tests gave random serum testosterone < 0.025 ng/mL, luteinizing hormone (LH) < 0.1 mIU/mL, follicle-stimulating hormone (FSH) 0.626 mIU/mL, thyroid-stimulating hormone (TSH) 6.85 microIU/mL, and fT4 6.96 pmol/L. Sella magnetic resonance imaging (MRI) showed no pituitary stalk enhancement. The response in the combined pituitary function test revealed multiple hormonal defects, while the TSH response to thyrotropin-releasing hormone (TRH) was exaggerated and delayed. Therefore, we concluded that pituitary stalk dysgenesis had led to hypothalamic-type panhypopituitarism.

Serum Vitamin D Status and Its Relationship to Metabolic Parameters in Patients with Type 2 Diabetes Mellitus / 전남의대학술지

The potential relationship between vitamin D (VitD) status and metabolic control in patients with type 2 diabetes mellitus (T2DM) warrants further study. We aimed to evaluate the relationship between the serum 25-hydroxyvitamin D [25(OH)D] level and various parameters in patients with T2DM. We analyzed retrospectively data from 276 Korean patients with T2DM whose serum 25(OH)D level was measured in our hospital. Nondiabetic healthy subjects who visited the hospital for health screening were selected as the control group (Non-DM, n=160). Compared with control subjects, patients with T2DM had a lower serum 25(OH)D level (15.4+/-0.5 vs. 12.9+/-0.4 ng/ml, p<0.01). Eleven percent of T2DM patients were VitD "insufficient" (20-29 ng/ml) and 87% of the patients were VitD "deficient" (<20 ng/ml). The serum 25(OH)D level was significantly related to serum fibrinogen, triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), ferritin, the urine albumin creatinine ratio, and hemoglobin A1C (HbA1C). In a multivariate logistic regression analysis, high levels of HbA1C, TG, and LDL-C were independently associated with VitD deficiency in T2DM patients. The results of the present study show that the majority of Koreans with T2DM are VitD deficient, and the serum 25(OH)D level in patients with T2DM is related to lipid and glucose parameters. Further studies are required of the relationship of VitD with fibrinogen and other related parameters.

Correlations between Glucagon Stimulated C-peptide Levels and Microvascular Complications in Type 2 Diabetes Patients

BACKGROUND: This study aimed to investigate whether stimulated C-peptide is associated with microvascular complications in type 2 diabetes mellitus (DM). METHODS: A cross-sectional study was conducted in 192 type 2 diabetic patients. Plasma basal C-peptide and stimulated C-peptide were measured before and 6 minutes after intravenous injection of 1 mg glucagon. The relationship between C-peptide and microvascular complications was statistically analyzed. RESULTS: In patients with retinopathy, basal C-peptide was 1.9+/-1.2 ng/mL, and stimulated C-peptide was 2.7+/-1.6 ng/mL; values were significantly lower compared with patients without retinopathy (P=0.031 and P=0.002, respectively). In patients with nephropathy, basal C-peptide was 1.6+/-0.9 ng/mL, and stimulated C-peptide was 2.8+/-1.6 ng/mL; values were significantly lower than those recorded in patients without nephropathy (P=0.020 and P=0.026, respectively). Stimulated C-peptide level was associated with increased prevalence of microvascular complications. Age-, DM duration-, and hemoglobin A1c-adjusted odds ratios for retinopathy in stimulated C-peptide value were 4.18 (95% confidence interval [CI], 1.40 to 12.51) and 3.35 (95% CI, 1.09 to 10.25), respectively. The multiple regression analysis between nephropathy and C-peptide showed that stimulated C-peptide was statistically correlated with nephropathy (P=0.03). CONCLUSION: In patients with type 2 diabetes, the glucagon stimulation test was a relatively simple method of short duration for stimulating C-peptide response. Stimulated C-peptide values were associated with microvascular complications to a greater extent than basal C-peptides.

Serum Vitamin D Status and Its Relationship to Metabolic Parameters in Patients with Type 2 Diabetes Mellitus / 전남의대학술지

The potential relationship between vitamin D (VitD) status and metabolic control in patients with type 2 diabetes mellitus (T2DM) warrants further study. We aimed to evaluate the relationship between the serum 25-hydroxyvitamin D [25(OH)D] level and various parameters in patients with T2DM. We analyzed retrospectively data from 276 Korean patients with T2DM whose serum 25(OH)D level was measured in our hospital. Nondiabetic healthy subjects who visited the hospital for health screening were selected as the control group (Non-DM, n=160). Compared with control subjects, patients with T2DM had a lower serum 25(OH)D level (15.4+/-0.5 vs. 12.9+/-0.4 ng/ml, p<0.01). Eleven percent of T2DM patients were VitD "insufficient" (20-29 ng/ml) and 87% of the patients were VitD "deficient" (<20 ng/ml). The serum 25(OH)D level was significantly related to serum fibrinogen, triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), ferritin, the urine albumin creatinine ratio, and hemoglobin A1C (HbA1C). In a multivariate logistic regression analysis, high levels of HbA1C, TG, and LDL-C were independently associated with VitD deficiency in T2DM patients. The results of the present study show that the majority of Koreans with T2DM are VitD deficient, and the serum 25(OH)D level in patients with T2DM is related to lipid and glucose parameters. Further studies are required of the relationship of VitD with fibrinogen and other related parameters.

Ca(2+)-induced Ca2+ Release from Internal Stores in INS-1 Rat Insulinoma Cells

The secretion of insulin from pancreatic beta-cells is triggered by the influx of Ca2+ through voltage-dependent Ca2+ channels. The resulting elevation of intracellular calcium ([Ca2+]i) triggers additional Ca2+ release from internal stores. Less well understood are the mechanisms involved in Ca2+ mobilization from internal stores after activation of Ca2+ influx. The mobilization process is known as calcium-induced calcium release (CICR). In this study, our goal was to investigate the existence of and the role of caffeine-sensitive ryanodine receptors (RyRs) in a rat pancreatic beta-cell line, INS-1 cells. To measure cytosolic and stored Ca2+, respectively, cultured INS-1 cells were loaded with fura-2/AM or furaptra/AM. [Ca2+]i was repetitively increased by caffeine stimulation in normal Ca2+ buffer. However, peak [Ca2+]i was only observed after the first caffeine stimulation in Ca2+ free buffer and this increase was markedly blocked by ruthenium red, a RyR blocker. KCl-induced elevations in [Ca2+]i were reduced by pretreatment with ruthenium red, as well as by depletion of internal Ca2+ stores using cyclopiazonic acid (CPA) or caffeine. Caffeine-induced Ca2+ mobilization ceased after the internal stores were depleted by carbamylcholine (CCh) or CPA. In permeabilized INS-1 cells, Ca2+ release from internal stores was activated by caffeine, Ca2+, or ryanodine. Furthermore, ruthenium red completely blocked the CICR response in permeabilized cells. RyRs were widely distributed throughout the intracellular compartment of INS-1 cells. These results suggest that caffeine-sensitive RyRs exist and modulate the CICR response from internal stores in INS-1 pancreatic beta-cells.

GLP-1 Can Protect Proinflammatory Cytokines Induced Beta Cell Apoptosis through the Ubiquitination

BACKGROUND: Proinflammatory cytokines are one of the causes of diabetes mellitus. However, the exact molecular mechanism by which proinflammatory cytokines induce beta-cell death remains to be clearly elucidated. Glucagon-like peptide-1 (GLP-1) affects the stimulation of insulin secretion and the preservation of beta-cells. Additionally, it may exert an antiapoptotic effect on beta cells; however, the mechanism underlying this effect has yet to be demonstrated. Therefore, we investigated the protective effects of GLP-1 in endoplasmic reticulum (ER)-mediated beta-cell apoptosis using proinflammatory cytokines. METHODS: To induce ER stress, hamster insulin-secreting tumor (HIT)-T15 cells were treated using a mixture of cytokines. Apoptosis was evaluated via MTT assay, Hoechst 33342 staining, and annexin/propidium iodide (PI) flow cytometry. The mRNA and protein expression levels of ER stress-related molecules were determined via PCR and Western blotting, respectively. Nitric oxide was measured with Griess reagent. The levels of inducible nitric oxide synthase (iNOS) mRNA and protein were analyzed via real-time PCR and Western blot, respectively. iNOS protein degradation was evaluated via immunoprecipitation. We pretreated HIT-T15 cells with exendin (Ex)-4 for 1 hour prior to the induction of stress. RESULTS: We determined that Ex-4 exerted a protective effect through nitric oxide and the modulation of ER stress-related molecules (glucose-regulated protein [GRP]78, GRP94, and CCAAT/enhancer-binding protein homologous protein [CHOP]) and that Ex-4 stimulates iNOS protein degradation via the ubiquitination pathway. Additionally, Ex-4 also induced the recovery of insulin2 mRNA expression in beta cells. CONCLUSION: The results of this study indicate that GLP-1 may protect beta cells against apoptosis through the ubiquitination pathway.