OBJECTIVE: To elucidate the effect of Huanglian-Renshen-Decoction (HRD) on ameliorating type 2 diabetes mellitus by maintaining islet β -cell identity through regulating paracrine and endocrine glucagon-like peptide-1 (GLP-1)/GLP-1 receptor (GLP-1R) in both islet and intestine. METHODS: The db/db mice were divided into the model (distilled water), low-dose HRD (LHRD, 3 g/kg), high-dose HRD (HHRD, 6 g/kg), and liraglutide (400 µ g/kg) groups using a random number table, 8 mice in each group. The db/m mice were used as the control group (n=8, distilled water). The entire treatment of mice lasted for 6 weeks. Blood insulin, glucose, and GLP-1 levels were quantified using enzyme-linked immunosorbent assay kits. The proliferation and apoptosis factors of islet cells were determined by immunohistochemistry (IHC) and immunofluorescence (IF) staining. Then, GLP-1, GLP-1R, prohormone convertase 1/3 (PC1/3), PC2, v-maf musculoaponeurotic fibrosarcoma oncogene homologue A (MafA), and pancreatic and duodenal homeobox 1 (PDX1) were detected by Western blot, IHC, IF, and real-time quantitative polymerase chain reaction, respectively. RESULTS: HRD reduced the weight and blood glucose of the db/db mice, and improved insulin sensitivity at the same time (P<0.05 or P<0.01). HRD also promoted mice to secrete more insulin and less glucagon (P<0.05 or P<0.01). Moreover, it also increased the number of islet β cell and decreased islet α cell mass (P<0.01). After HRD treatment, the levels of GLP-1, GLP-1R, PC1/3, PC2, MafA, and PDX1 in the pancreas and intestine significantly increased (P<0.05 or P<0.01). CONCLUSION HRD can maintain the normal function and identity of islet β cell, and the underlying mechanism is related to promoting the paracrine and endocrine activation of GLP-1 in pancreas and intestine.
Animals ; Glucagon-Like Peptide 1/metabolism* ; Diabetes Mellitus, Type 2/metabolism* ; Glucagon-Like Peptide-1 Receptor/metabolism* ; Insulin-Secreting Cells/pathology* ; Drugs, Chinese Herbal/pharmacology* ; Male ; Blood Glucose/metabolism* ; Insulin/blood* ; Mice ; Intestinal Mucosa/pathology* ; Apoptosis/drug effects* ; Cell Proliferation/drug effects* ; Islets of Langerhans/pathology*

Humans ; Glucagon-Like Peptide-1 Receptor/agonists* ; Diabetic Cardiomyopathies/drug therapy* ; Diabetes Mellitus, Type 2

Obesity is an important risk factor of type 2 diabetes (T2D), which has become an important factor threatening human health. However, no perfect drug choice for obesity exists. Semaglutide is a kind of human glucagon-like peptide-1 (GLP-1) analog that promotes insulin secretion while inhibiting glucagon secretion through a glucose concentration-dependent mechanism. GLP-1 can also delay stomach emptying and suppress appetite to help lose weight. This review summarizes clinical evidence of the semaglutide effect on T2D and obesity and establishes expectations on future clinical trials for obesity treatment.
Diabetes Mellitus, Type 2/drug therapy* ; Glucagon-Like Peptide-1 Receptor/therapeutic use* ; Glucagon-Like Peptides ; Humans ; Hypoglycemic Agents/therapeutic use* ; Motivation ; Obesity/drug therapy*

Weight loss is an important goal in the management of several chronic conditions, including type 2 diabetes mellitus, and pharmacological therapies that aid weight loss are appealing. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter 2 inhibitors (SGLT2is) are novel glucose-lowering therapies that have been shown to induce clinically significant reductions in body weight. However, this weight loss may not be attributed solely to fat mass (FM). Given the importance of skeletal muscle and lean body mass (LBM) on cardio-metabolic health and physical function, we reviewed the available literature reporting the effects of GLP-1RAs and SGLT2is on body composition. Results demonstrate that, in most circumstances, the weight loss associated with both therapies predominantly comprises a reduction in FM, although significant heterogeneity exists between studies. In over half of the studies identified, the proportion of LBM reduction ranged between 20% and 50% of total weight lost, which is consistent with diet-induced weight loss and bariatric surgery. No clear differences existed between GLP-1RAs and SGLT2is. Consequently, the loss of LBM and skeletal muscle associated with weight loss induced by GLP-1RAs and SGLT2is warrants attention. Strategies to preserve skeletal muscle and improve physical function, for example through structured exercise, are of great importance.
Bariatric Surgery ; Body Composition ; Body Weight ; Diabetes Mellitus, Type 2 ; Glucagon-Like Peptide 1 ; Glucagon-Like Peptide-1 Receptor ; Humans ; Muscle, Skeletal ; Population Characteristics ; Weight Loss

OBJECTIVE: To investigate the effect of glucagon-like peptide 1 receptor agonists (GLP-1RAs) on body fat redistribution and muscle mass in overweight/obese patients with type 2 diabetes (T2DM). METHODS: We retrospectively analyzed the data of 76 patients with body mass indexes (BMI)≥24 kg/m, who had an established diagnosis of T2DM in our department between December, 2014 and September, 2015. We divided these patients according to their BMI in overweight group (BMI of 24-27.9 kg/m, =14), obese group (BMI of 28-31.9 kg/m, =35) and severely obese group (BMI≥32 kg/m, =27). All the patients received treatment with GLP-1RAs (Exenatide or Liraglutide) for 3.0 to 29.0 weeks (mean 8.9 weeks), and their blood glucose, HbA1c and serum lipids were analyzed. For each patient, the fat and muscle masses were analyzed using a human body composition analyzer (JAWON-IOI353, Korea) before and after GLP-1RAs treatment. RESULTS: Treatment with GLP-1RAs significantly decreased BMI and visceral adiposity index (VAI) in all the patients in the 3 groups ( < 0.05). The treatment significantly decreased the body weight in the overweight group and obese group by 2.70 kg (0.60-4.95 kg) and 2.65 kg (1.45-6.40 kg), respectively ( < 0.05), and significantly decreased the waist-to-hip ratio (WHR) in the overweight group ( < 0.05). The obese and severely obese patients showed significantly decreased percentage body fat (including both subcutaneous and visceral fat) and increased muscle mass after the treatment ( < 0.05). Compared with those in the overweight group, the percentage body fat and VAI were significantly decreased in the obese group after the treatment ( < 0.05), and the percentage of subcutaneous fat reduced and the muscle ratio increased more obviously in the obese and severely obese patients ( < 0.05). CONCLUSIONS GLP-1RAs treatment can significantly lower BMI and improve body fat distribution in obese patients with T2DM, especially in patients with a greater BMI.
Adipose Tissue ; Body Mass Index ; Diabetes Mellitus, Type 2 ; Glucagon-Like Peptide-1 Receptor ; Humans ; Hypoglycemic Agents ; Obesity ; Overweight ; Retrospective Studies

The management of type 2 diabetes mellitus should comprise healthy lifestyle modifications along with tailored pharmacologic treatment. Traditionally, the American Diabetes Association (ADA)'s Diabetes Management Guidelines have not prioritized specific anti-diabetic drugs over others with regard to cardiovascular disease (CVD) and mortality prevention. Recently, two novel anti-diabetic medications proved to be significantly protective against future CVD and mortality, regardless of the glycemic levels achieved in type 2 diabetic patients with pre-existing CVD. The 2018 ADA Guidelines recommend SGLT2 inhibitor and/or GLP-1 receptor agonist be used for type 2 diabetes patients with atherosclerotic CVD after metformin monotherapy failure. Considering the value of CVD protection in the management of diabetes mellitus, this minor guideline adjustment could have far-reaching implications.
Cardiovascular Diseases ; Diabetes Mellitus ; Diabetes Mellitus, Type 2 ; Glucagon-Like Peptide-1 Receptor ; Humans ; Life Style ; Metformin ; Mortality ; Sodium-Glucose Transporter 2

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) were recommended as a monotherapy or combination therapy with oral hypoglycemic agents or basal insulin in the position statement of the Korean Diabetes Association 2017 for pharmacological therapy, which was a change from the previous guideline that recommended them only as a combination therapy. Many randomized clinical trials and systematic reviews report that GLP-1RAs have considerable glucose-lowering effect and lead to weight reduction and low risk of hypoglycemia when used as a monotherapy or combination therapy. The results of cardiovascular outcome trials of long-acting GLP-1RAs (liraglutide, semaglutide) have demonstrated cardiovascular benefits in subjects with type 2 diabetes mellitus and a high risk of cardiovascular disease. The GLP-1RAs may be a choice of therapy when weight control and avoidance of hypoglycemia are important, and patients with high risk of cardiovascular disease might also favor choosing GLP-1RA.
Cardiovascular Diseases ; Diabetes Mellitus ; Diabetes Mellitus, Type 2* ; Glucagon-Like Peptide 1* ; Glucagon-Like Peptide-1 Receptor* ; Humans ; Hypoglycemia ; Hypoglycemic Agents ; Insulin ; Obesity ; Weight Loss

Glucagon like peptide-1 (GLP-1) stimulates glucose-dependent insulin secretion. Dipeptidyl peptidase-4 (DPP-4) inhibitors, which block inactivation of GLP-1, are currently in clinical use for type 2 diabetes mellitus. Recently, GLP-1 has also been reported to have neuroprotective effects in cases of cerebral ischemia. We therefore investigated the neuroprotective effects of GLP-1 receptor (GLP-1R) agonist, exendin-4 (ex-4), after cerebral ischemia-reperfusion injury. Transient middle cerebral artery occlusion (tMCAO) was induced in rats by intracerebroventricular (i.c.v.) administration of ex-4 or ex9-39. Oxygen-glucose deprivation was also induced in primary neurons, bEnd.3 cells, and BV-2. Ischemia-reperfusion injury reduced expression of GLP-1R. Additionally, higher oxidative stress in SOD2 KO mice decreased expression of GLP-1R. Downregulation of GLP-1R by ischemic injury was 70% restored by GLP-1R agonist, ex-4, which resulted in significant reduction of infarct volume. Levels of intracellular cyclic AMP, a second messenger of GLP-1R, were also increased by 2.7-fold as a result of high GLP-1R expression. Moreover, our results showed that ex-4 attenuated pro-inflammatory cyclooxygenase-2 (COX-2) and prostaglandin E₂ after MCAO. C-Jun NH₂ terminal kinase (JNK) signaling, which stimulates activation of COX-2, was 36% inhibited by i.c.v. injection of ex-4 at 24 h. Islet-brain 1 (IB1), a scaffold regulator of JNK, was 1.7-fold increased by ex-4. GLP-1R activation by ex-4 resulted in reduction of COX-2 through increasing IB1 expression, resulting in anti-inflammatory neuroprotection during stroke. Our study suggests that the anti-inflammatory action of GLP-1 could be used as a new strategy for the treatment of neuroinflammation after stroke accompanied by hyperglycemia.
Animals ; Brain Ischemia ; Cyclic AMP ; Cyclooxygenase 2 ; Diabetes Mellitus, Type 2 ; Down-Regulation ; Glucagon* ; Glucagon-Like Peptide 1 ; Glucagon-Like Peptide-1 Receptor ; Hyperglycemia ; Infarction, Middle Cerebral Artery ; Insulin ; Mice ; Neurons ; Neuroprotection ; Neuroprotective Agents ; Oxidative Stress ; Phosphotransferases ; Rats ; Reperfusion Injury ; Second Messenger Systems ; Stroke*

BACKGROUND: The prevalence of type 2 diabetes mellitus (T2DM) and obesity is increasing in Korea. Clinical studies in patients with T2DM have shown that combining the glucagon-like peptide-1 receptor agonist exenatide twice daily with basal insulin is an effective glucose-lowering strategy. However, these studies were predominantly conducted in non-Asian populations. METHODS: We conducted a subgroup analysis of data from a multinational, 30-week, randomized, open-label trial to compare the effects of exenatide twice daily (n=10) or three times daily mealtime insulin lispro (n=13) among Korean patients with T2DM inadequately controlled (glycosylated hemoglobin [HbA1c] >7.0%) on metformin plus optimized insulin glargine. RESULTS: Exenatide twice daily and insulin lispro both reduced HbA1c (mean −1.5% and −1.0%, respectively; P<0.01 vs. baseline). Fasting glucose and weight numerically decreased with exenatide twice daily (−0.7 mmol/L and −0.7 kg, respectively) and numerically increased with insulin lispro (0.9 mmol/L and 1.0 kg, respectively). Minor hypoglycemia occurred in four patients receiving exenatide twice daily and three patients receiving insulin lispro. Gastrointestinal adverse events were the most common with exenatide twice daily treatment. CONCLUSION: This analysis found treatment with exenatide twice daily improved glycemic control without weight gain in Korean patients with T2DM unable to achieve glycemic control on metformin plus basal insulin.
Diabetes Mellitus, Type 2* ; Fasting ; Glucagon-Like Peptide-1 Receptor ; Glucose ; Humans ; Hypoglycemia ; Insulin Glargine ; Insulin Lispro* ; Insulin* ; Korea ; Meals ; Metformin ; Obesity ; Prevalence ; Weight Gain

It is well known that both insulin resistance and decreased insulin secretory capacity are important factors in the pathogenesis of type 2 diabetes mellitus (T2DM). In addition to genetic factors, obesity and lipotoxicity can increase the risk of T2DM. Glucagon-like peptide 1 (GLP-1) receptor agonists are novel antidiabetic drugs with multiple effects. They can stimulate glucose-dependent insulin secretion, inhibit postprandial glucagon release, delay gastric emptying, and induce pancreatic β-cell proliferation. They can also reduce the weight of patients with T2DM and relieve lipotoxicity at the cellular level. Many intracellular targets of GLP-1 have been found, but more remain to be identified. Elucidating these targets could be a basis for developing new potential drugs. My colleagues and I have investigated new targets of GLP-1, with a particular focus on pancreatic β-cell lines and hepatic cell lines. Herein, I summarize the recent work from my laboratory, with profound gratitude for receiving the prestigious 2016 Namgok Award.
Awards and Prizes ; Diabetes Mellitus ; Diabetes Mellitus, Type 2 ; Gastric Emptying ; Glucagon ; Glucagon-Like Peptide 1* ; Glucagon-Like Peptide-1 Receptor ; Hepatocytes* ; Humans ; Hypoglycemic Agents ; Insulin ; Insulin Resistance ; Obesity