Type 2 diabetes mellitus (T2DM) is a current global health priority and Asia is the epicenter of this epidemic disease. Unlike in the west, where older population is most affected, the burden of diabetes in Asian countries is disproportionately high in young to middle-age adults. The incidence of diabetic nephropathy is alarmingly high in patients with early onset T2DM, especially in those with poor glycemic control. How to control this chronic and debilitating disease is currently a very important health issue in Asia. Bariatric surgery has proven successful in treating not just obesity but also T2DM in morbid obese patients (body mass index [BMI] >35 kg/m2). Gastrointestinal metabolic surgery recently has been proposed as a new treatment modality for obesity related T2DM for patients with BMI <35 kg/m2. Many studies from Asia reported promising results of metabolic surgery to treat obese patients with T2DM which is not well controlled. It has been demonstrated that changes in gastrointestinal hormone secretion after gastrointestinal surgery would favor an early improvement of T2DM in Asians. New procedures have also been designed and proposed specifically for the treatment of diabetes in Asia. This article examines clinical trial data and accepted algorithms with a view toward elucidating the application of metabolic surgery for the treatment of T2DM in the Asia. We propose a systematic approach to surgical treatment, addressing current evidences, patient selection, procedure of choice, and timing and guideline for new procedures.
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Obesity has quickly become a worldwide pandemic, causing major adverse health outcomes such as dyslipidemia, type 2 diabetes mellitus, cardiovascular disease and cancers. Obesity-induced insulin resistance is the key for developing these metabolic disorders, and investigation to understand the molecular mechanisms involved has been vibrant for the past few decades. Of these, low-grade chronic inflammation is suggested as a critical concept in the development of obesity-induced insulin resistance, and the anti-inflammatory effect of nitric oxide (NO) signaling has been reported to be linked to improvement of insulin resistance in multiple organs involved in glucose metabolism. Recently, a body of evidence suggested that vasodilatory-stimulated phosphoprotein (VASP), a downstream mediator of NO signaling plays a crucial role in the anti-inflammatory effect and improvement of peripheral insulin resistance. These preclinical studies suggest that NO/VASP signaling could be an ideal therapeutic target in the treatment of obesity-related metabolic dysfunction. In this review, we introduce studies that investigated the protective role of NO/VASP signaling against obesity-related inflammation and insulin resistance in various tissues.
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Despite overall reductions in heart disease prevalence, the risk of developing heart failure has remained 2-fold greater among people with diabetes. Growing evidence has supported that fluctuations in glucose level and uptake contribute to cardiovascular disease (CVD) by modifying proteins, DNA, and gene expression. In the case of glucose, clinical studies have shown that increased dietary sugars for healthy individuals or poor glycemic control in diabetic patients further increased CVD risk. Furthermore, even after decades of maintaining tight glycemic control, susceptibility to disease progression can persist following a period of poor glycemic control through a process termed "glycemic memory." In response to chronically elevated glucose levels, a number of studies have identified molecular targets of the glucose-mediated protein posttranslational modification by the addition of an
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Hypoglycemia has been considered as a major barrier to achieving the proper glycemic target in type 2 diabetes mellitus patients. In particular, severe hypoglycemia (SH), which is defined as a hypoglycemic episode requiring the assistance of another person to raise the patient's glucose level, is a serious complication of diabetes because of its possible fatal outcomes. Recently, the recommendations for diabetes care have emphasized a patient-centered approach, considering the individualized patient factors including hypoglycemia. Many studies have been performed which analyzed the risk factors and clinical outcomes for SH. From the studies, researchers recommend that targeting a less stringent glycosylated hemoglobin level and selecting a safer class of drugs for hypoglycemia are appropriate for patients with a high risk of SH. Also, careful clinical attention to prevent hypoglycemia, including intensive education, is necessary to minimize the risk of SH and SH-related fatal outcomes.
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Bariatric surgery, initially intended as a weight-loss procedure, is superior to standard lifestyle intervention and pharmacological therapy for type 2 diabetes in obese individuals. Intensive medical management of hyperglycemia is associated with improved microvascular outcomes. Whether or not the reduction in hyperglycemia observed after bariatric surgery translates to improved microvascular outcomes is yet to be determined. There is substantial heterogeneity in the data relating to the impact of bariatric surgery on diabetic retinopathy (DR), the most common microvascular complication of diabetes. This review aims to collate the recent data on retinal outcomes after bariatric surgery. This comprehensive evaluation revealed that the majority of DR cases remain stable after surgery. However, risk of progression of pre-existing DR and the development of new DR is not eliminated by surgery. Instances of regression of DR are also noted. Potential risk factors for deterioration include severity of DR at the time of surgery and the magnitude of glycated hemoglobin reduction. Concerns also exist over the detrimental effects of postprandial hypoglycemia after surgery.
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Dipeptidyl peptidase-4 (DPP-4) inhibitors are a new class of oral antidiabetic agent for the treatment of type 2 diabetes mellitus. They increase endogenous levels of incretin hormones, which stimulate glucose-dependent insulin secretion, decrease glucagon secretion, and contribute to reducing postprandial hyperglycemia. Although DPP-4 inhibitors have similar benefits, they can be differentiated in terms of their chemical structure, pharmacology, efficacy and safety profiles, and clinical considerations. Gemigliptin (brand name: Zemiglo), developed by LG Life Sciences, is a potent, selective, competitive, and long acting DPP-4 inhibitor. Various studies have shown that gemigliptin is an optimized DPP-4 inhibitor in terms of efficacy, safety, and patient compliance for treatment of type 2 diabetes mellitus. In this review, we summarize the characteristics of gemigliptin and discuss its potential benefits in clinical practice.
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The purpose of this study was to examine the effect of regular exercise training on insulin sensitivity in adults with type 2 diabetes mellitus (T2DM) using the pooled data available from randomised controlled trials. In addition, we sought to determine whether short-term periods of physical inactivity diminish the exercise-induced improvement in insulin sensitivity. Eligible trials included exercise interventions that involved ≥3 exercise sessions, and reported a dynamic measurement of insulin sensitivity. There was a significant pooled effect size (ES) for the effect of exercise on insulin sensitivity (ES, –0.588; 95% confidence interval [CI], –0.816 to –0.359;
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Antidiabetic Effects of Physical Activity: How It Helps to Control Type 2 Diabetes
Obesity resulting from the delivery of an excess amount of energy to adipose tissue from glucose or free fatty acids is associated with insulin resistance and adipose tissue inflammation. Reactive oxygen species (ROS) have been implicated as contributors to both the onset and the progression of insulin resistance. ROS can be generated by overloading the mitochondrial oxidative phosphorylation system, and also by nicotinamide adenine dinucleotide phosphate oxidases (NOX) produced by either adipocytes, which only produce NOX4, or by macrophages, which produce mainly NOX2. The source of the ROS might differ in the early, intermediate and late stages of obesity, switching from NOX4-dependence in the early phases to NOX2-dependence, in the intermediate phase, and transiting to mitochondria-dependence later in the time course of obesity. Thus, depending on the stage of obesity, ROS can be generated by three distinct mechanisms: i.e., NOX4, NOX2, and mitochondria. In this review, we will discuss whether NOX4-, NOX2-, and/or mitochondria-derived ROS is/are causal in the onset of adipocyte insulin resistance as obesity progresses. Moreover, we will review the pathophysiological roles of NOX4, NOX2, and mitochondria-derived ROS on adipose tissue inflammation.
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In the early 2000s, the prevalence of diabetes in adults aged ≥30 years in Korea was about 9% to 10%, and it remained stable. However, a nationwide survey showed that this prevalence increased over the past few years. After age-standardization using the Korean population of the year 2010, the prevalence of diabetes in adults aged ≥30 years was 10.0% to 10.8% between 2001 and 2012, which increased to 12.5% in 2013 and 11.6% in 2014. During that period, there have been changes in the gender- and age-specific prevalence of diabetes in Korean adults. The prevalence of diabetes in the elderly population increased significantly, while this prevalence in young adults, especially in young women, did not change significantly. The contribution of each diabetic risk factor, such as obesity, β-cell dysfunction, sarcopenia, and socioeconomic status, in developing diabetes has also changed during that period in each gender and age group. For young women, obesity was the most important risk factor; by contrast, for elderly diabetic patients, sarcopenia was more important than obesity as a risk factor. Considering the economic burden of diabetes and its associated comorbidities, a public health policy targeting the major risk factors in each population might be more effective in preventing diabetes.
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Type 2 diabetes mellitus (T2DM) is a multifactorial disease with a complex and progressive pathogenesis. The two primary mechanisms of T2DM pathogenesis are pancreatic β-cell dysfunction and insulin resistance. Pancreatic β-cell dysfunction is recognized to be a prerequisite for the development of T2DM. Therapeutic modalities that improve β-cell function are considered critical to T2DM management; however, blood glucose control remains a challenge for many patients due to suboptimal treatment efficacy and the progressive nature of T2DM. Incretin-based therapies are now the most frequently prescribed antidiabetic drugs in Korea. Incretin-based therapies are a favorable class of drugs due to their ability to reduce blood glucose by targeting the incretin hormone system and, most notably, their potential to improve pancreatic β-cell function. This review outlines the current understanding of the incretin hormone system in T2DM and summarizes recent updates on the effect of incretin-based therapies on β-cell function and β-cell mass in animals and humans.
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Serotonin (5-hydroxytryptamine [5-HT]) is a monoamine that has various functions in both neuronal and non-neuronal systems. In the central nervous system, 5-HT regulates mood and feeding behaviors as a neurotransmitter. Thus, there have been many trials aimed at increasing the activity of 5-HT in the central nervous system, and some of the developed methods are already used in the clinical setting as anti-obesity drugs. Unfortunately, some drugs were withdrawn due to the development of unwanted peripheral side effects, such as valvular heart disease and pulmonary hypertension. Recent studies revealed that peripheral 5-HT plays an important role in metabolic regulation in peripheral tissues, where it suppresses adaptive thermogenesis in brown adipose tissue. Inhibition of 5-HT synthesis reduced the weight gain and improved the metabolic dysfunction in a diet-induced obesity mouse model. Genome-wide association studies also revealed genetic associations between the serotonergic system and obesity. Several genetic polymorphisms in tryptophan hydroxylase and 5-HT receptors were shown to have strong associations with obesity. These results support the clinical significance of the peripheral serotonergic system as a therapeutic target for obesity and diabetes.
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Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease in adults and children worldwide. NAFLD has become a severe health issue and it can progress towards a more severe form of the disease, the non-alcoholic steatohepatitis (NASH). A combination of environmental factors, host genetics, and gut microbiota leads to excessive accumulation of lipids in the liver (steatosis), which may result in lipotoxicity and trigger hepatocyte cell death, liver inflammation, fibrosis, and pathological angiogenesis. NASH can further progress towards liver cirrhosis and cancer. Over the last few years, cell-derived extracellular vesicles (EVs) have been identified as effective cell-to-cell messengers that transfer several bioactive molecules in target cells, modulating the pathogenesis and progression of NASH. In this review, we focused on recently highlighted aspects of molecular pathogenesis of NASH, mediated by EVs via their bioactive components. The studies included in this review summarize the state of art regarding the role of EVs during the progression of NASH and bring novel insight about the potential use of EVs for diagnosis and therapeutic strategies for patients with this disease.
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Fibroblast growth factor 21 (FGF21) is a metabolic hormone with pleiotropic effects on energy metabolism and insulin sensitivity. Besides its antiobese and antidiabetic activity, FGF21 also possesses the protective effects against atherosclerosis. Circulating levels of FGF21 are elevated in patients with atherosclerosis, macrovascular and microvascular complications of diabetes, possibly due to a compensatory upregulation. In apolipoprotein E-deficient mice, formation of atherosclerotic plaques is exacerbated by genetic depletion of FGF21, but is attenuated upon replenishment with recombinant FGF21. However, the blood vessel is not the direct target of FGF21, and the antiatherosclerotic activity of FGF21 is attributed to its actions in adipose tissues and liver. In adipocytes, FGF21 promotes secretion of adiponectin, which in turn acts directly on blood vessels to reduce endothelial dysfunction, inhibit proliferation of smooth muscle cells and block conversion of macrophages to foam cells. Furthermore, FGF21 suppresses cholesterol biosynthesis and attenuates hypercholesterolemia by inhibiting the transcription factor sterol regulatory element-binding protein-2 in hepatocytes. The effects of FGF21 on elevation of adiponectin and reduction of hypercholesterolemia are also observed in a phase-1b clinical trial in patients with obesity and diabetes. Therefore, FGF21 exerts its protection against atherosclerosis by fine-tuning the interorgan crosstalk between liver, brain, adipose tissue, and blood vessels.
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Brown fat is a specialized fat depot that can increase energy expenditure and produce heat. After the recent discovery of the presence of active brown fat in human adults and novel transcription factors controlling brown adipocyte differentiation, the field of the study of brown fat has gained great interest and is rapidly growing. Brown fat expansion and/or activation results in increased energy expenditure and a negative energy balance in mice and limits weight gain. Brown fat is also able to utilize blood glucose and lipid and results in improved glucose metabolism and blood lipid independent of weight loss. Prolonged cold exposure and beta adrenergic agonists can induce browning of white adipose tissue. The inducible brown adipocyte, beige adipocyte evolving by thermogenic activation of white adipose tissue have different origin and molecular signature from classical brown adipocytes but share the characteristics of high mitochondria content, UCP1 expression and thermogenic capacity when activated. Increasing browning may also be an efficient way to increase whole brown fat activity. Recent human studies have shown possibilities that findings in mice can be reproduced in human, making brown fat a good candidate organ to treat obesity and its related disorders.
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Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes that is characterized by an early onset, autosomal dominant mode of inheritance and a primary defect in pancreatic β-cell function. MODY represents less than 2% of all diabetes cases and is commonly misdiagnosed as type 1 or type 2 diabetes mellitus. At least 13 MODY subtypes with distinct genetic etiologies have been identified to date. A correct genetic diagnosis is important as it often leads to personalized treatment for those with diabetes and enables predictive genetic testing for their asymptomatic relatives. Next-generation sequencing may provide an efficient method for screening mutations in this form of diabetes as well as identifying new MODY genes. In this review, I discuss a current update on MODY in the literatures and cover the studies that have been performed in Korea.
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