Role of SUMO-Specific Protease 2 in Leptin-Induced Fatty Acid Metabolism in White Adipocytes

Background@#Leptin is a 16-kDa fat-derived hormone with a primary role in controlling adipose tissue levels. Leptin increases fatty acid oxidation (FAO) acutely through adenosine monophosphate-activated protein kinase (AMPK) and on delay through the SUMO-specific protease 2 (SENP2)–peroxisome proliferator-activated receptor δ/γ (PPARδ/γ) pathway in skeletal muscle. Leptin also directly increases FAO and decreases lipogenesis in adipocytes; however, the mechanism behind these effects remains unknown. Here, we investigated the role of SENP2 in the regulation of fatty acid metabolism by leptin in adipocytes and white adipose tissues. @*Methods@#The effects of leptin mediated by SENP2 on fatty acid metabolism were tested by siRNA-mediated knockdown in 3T3-L1 adipocytes. The role of SENP2 was confirmed in vivo using adipocyte-specific Senp2 knockout (Senp2-aKO) mice. We revealed the molecular mechanism involved in the leptin-induced transcriptional regulation of carnitine palmitoyl transferase 1b (Cpt1b) and long-chain acyl-coenzyme A synthetase 1 (Acsl1) using transfection/reporter assays and chromatin immunoprecipitation. @*Results@#SENP2 mediated the increased expression of FAO-associated enzymes, CPT1b and ACSL1, which peaked 24 hours after leptin treatment in adipocytes. In contrast, leptin stimulated FAO through AMPK during the initial several hours after treatment. In white adipose tissues, FAO and mRNA levels of Cpt1b and Acsl1 were increased by 2-fold 24 hours after leptin injection in control mice but not in Senp2-aKO mice. Leptin increased PPARα binding to the Cpt1b and Acsl1 promoters in adipocytes through SENP2. @*Conclusion@#These results suggest that the SENP2-PPARα pathway plays an important role in leptin-induced FAO in white adipocytes.

Triglyceride-Glucose Index Predicts Future Atherosclerotic Cardiovascular Diseases: A 16-Year Follow-up in a Prospective, Community-Dwelling Cohort Study

Background@#While the triglyceride-glucose (TyG) index is a measure of insulin resistance, its association with cardiovascular disease (CVD) has not been well elucidated. We evaluated the TyG index for prediction of CVDs in a prospective large communitybased cohort. @*Methods@#Individuals 40 to 70 years old were prospectively followed for a median 15.6 years. The TyG index was calculated as the Ln [fasting triglycerides (mg/dL)×fasting glucose (mg/dL)/2]. CVDs included any acute myocardial infarction, coronary artery disease or cerebrovascular disease. We used a Cox proportional hazards model to estimate CVD risks according to quartiles of the TyG index and plotted the receiver operating characteristics curve for the incident CVD. @*Results@#Among 8,511 subjects (age 51.9±8.8 years; 47.5% males), 931 (10.9%) had incident CVDs during the follow-up. After adjustment for age, sex, body mass index, diabetes mellitus, hypertension, total cholesterol, smoking, alcohol, exercise, and C-reactive protein, subjects in the highest TyG quartile had 36% increased risk of incident CVD compared with the lowest TyG quartile (hazard ratio, 1.36; 95% confidence interval, 1.10 to 1.68). Carotid plaque, assessed by ultrasonography was more frequent in subjects in the higher quartile of TyG index (P for trend=0.049 in men and P for trend <0.001 in women). The TyG index had a higher predictive power for CVDs than the homeostasis model assessment of insulin resistance (HOMA-IR) (area under the curve, 0.578 for TyG and 0.543 for HOMA-IR). Adding TyG index on diabetes or hypertension alone gave sounder predictability for CVDs. @*Conclusion@#The TyG index is independently associated with future CVDs in 16 years of follow-up in large, prospective Korean cohort.

Genome-Wide Association Study on Longitudinal Change in Fasting Plasma Glucose in Korean Population

Background@#Genome-wide association studies (GWAS) on type 2 diabetes mellitus (T2DM) have identified more than 400 distinct genetic loci associated with diabetes and nearly 120 loci for fasting plasma glucose (FPG) and fasting insulin level to date. However, genetic risk factors for the longitudinal deterioration of FPG have not been thoroughly evaluated. We aimed to identify genetic variants associated with longitudinal change of FPG over time. @*Methods@#We used two prospective cohorts in Korean population, which included a total of 10,528 individuals without T2DM. GWAS of repeated measure of FPG using linear mixed model was performed to investigate the interaction of genetic variants and time, and meta-analysis was conducted. Genome-wide complex trait analysis was used for heritability calculation. In addition, expression quantitative trait loci (eQTL) analysis was performed using the Genotype-Tissue Expression project. @*Results@#A small portion (4%) of the genome-wide single nucleotide polymorphism (SNP) interaction with time explained the total phenotypic variance of longitudinal change in FPG. A total of four known genetic variants of FPG were associated with repeated measure of FPG levels. One SNP (rs11187850) showed a genome-wide significant association for genetic interaction with time. The variant is an eQTL for NOC3 like DNA replication regulator (NOC3L) gene in pancreas and adipose tissue. Furthermore, NOC3L is also differentially expressed in pancreatic β-cells between subjects with or without T2DM. However, this variant was not associated with increased risk of T2DM nor elevated FPG level. @*Conclusion@#We identified rs11187850, which is an eQTL of NOC3L, to be associated with longitudinal change of FPG in Korean population.

Partial Deletion of Perk Improved High-Fat Diet-Induced Glucose Intolerance in Mice

Although pancreatic endoplasmic reticulum kinase (PERK) is indispensable to beta cells, low-dose PERK inhibitor improved glucose- stimulated insulin secretion (GSIS) and hyperglycemia in diabetic mice. Current study examined if partial deletion of Perk (Perk+/-) recapitulated the effects of PERK inhibitor, on the contrary to the complete deletion. Perk+/- mice and wild-type controls were fed with a high-fat diet (HFD) for 23 weeks. Glucose tolerance was evaluated along with serum insulin levels and islet morphology. Perk+/- mice on normal chow were comparable to wild-type mice in various metabolic features. HFD-induced obesity was not influenced by Perk reduction; however, HFD-induced glucose intolerance was significantly improved since 15-week HFD. HFD-induced compromises in GSIS were relieved by Perk reduction, accompanied by reductions in phosphorylated PERK and activating transcription factor 4 (ATF4) in the islets. Meanwhile, HFD-induced islet expansion was not significantly affected. In summary, partial deletion of Perk improved glucose tolerance and GSIS impaired by diet-induced obesity, without changes in body weights or islet mass.

Comparison of Prevailing Insulin Regimens at Different Time Periods in Hospitalized Patients: A Real-World Experience from a Tertiary Hospital

Background@#Prevailing insulin regimens for glycemic control in hospitalized patients have changed over time. We aimed to determine whether the current basal-bolus insulin (BBI) regimen is superior to the previous insulin regimen, mainly comprising split-mixed insulin therapy. @*Methods@#This was a single tertiary center, retrospective observational study that included non-critically ill patients with type 2 diabetes mellitus who were treated with split-mixed insulin regimens from 2004 to 2007 (period 1) and with BBI from 2008 to 2018 (period 2). Patients from each period were analyzed after propensity score matching. The mean difference in glucose levels and the achievement of fasting and preprandial glycemic targets by day 6 of admission were assessed. The total daily insulin dose, incidence of hypoglycemia, and length of hospital stay were also evaluated. @*Results@#Among 244 patients from each period, both fasting glucose (estimated mean±standard error, 147.4±3.1 mg/dL vs. 129.4±3.2 mg/dL, P<0.001, day 6) and preprandial glucose (177.7±2.8 mg/dL vs. 152.8±2.8 mg/dL, P<0.001, day 6) were lower in period 2 than in period 1. By day 6 of hospital admission, 42.6% and 67.2% of patients achieved a preprandial glycemic target of <140 mg/dL in periods 1 and 2, respectively (relative risk, 2.00; 95% confidence interval, 1.54 to 2.59), without an increased incidence of hypoglycemia. Length of stay was shorter in period 2 (10.23±0.26 days vs. 8.70±0.26 days, P<0.001). @*Conclusion@#BBI improved glycemic control in a more efficacious manner than a split-mixed insulin regimen without increasing the risk of hypoglycemia in a hospital setting.

Efficacy and Safety of Self-Titration Algorithms of Insulin Glargine 300 units/mL in Individuals with Uncontrolled Type 2 Diabetes Mellitus (The Korean TITRATION Study): A Randomized Controlled Trial

Background@#To compare the efficacy and safety of two insulin self-titration algorithms, Implementing New Strategies with Insulin Glargine for Hyperglycemia Treatment (INSIGHT) and EDITION, for insulin glargine 300 units/mL (Gla-300) in Korean individuals with uncontrolled type 2 diabetes mellitus (T2DM). @*Methods@#In a 12-week, randomized, open-label trial, individuals with uncontrolled T2DM requiring basal insulin were randomized to either the INSIGHT (adjusted by 1 unit/day) or EDITION (adjusted by 3 units/week) algorithm to achieve a fasting self-monitoring of blood glucose (SMBG) in the range of 4.4 to 5.6 mmol/L. The primary outcome was the proportion of individuals achieving a fasting SMBG ≤5.6 mmol/L without noct urnal hypoglycemia at week 12. @*Results@#Of 129 individuals (age, 64.1±9.5 years; 66 [51.2%] women), 65 and 64 were randomized to the INSIGHT and EDITION algorithms, respectively. The primary outcome of achievement was comparable between the two groups (24.6% vs. 23.4%, P=0.876). Compared with the EDITION group, the INSIGHT group had a greater reduction in 7-point SMBG but a similar decrease in fasting plasma glucose and glycosylated hemoglobin. The increment of total daily insulin dose was significantly higher in the INSIGHT group than in the EDITION group (between-group difference: 5.8±2.7 units/day, P=0.033). However, body weight was significantly increased only in the EDITION group (0.6±2.4 kg, P=0.038). There was no difference in the occurrence of hypoglycemia between the two groups. Patient satisfaction was significantly increased in the INSIGHT group (P=0.014). @*Conclusion@#The self-titration of Gla-300 using the INSIGHT algorithm was effective and safe compared with that using the EDITION algorithm in Korean individuals with uncontrolled T2DM (ClinicalTrials.gov number: NCT03406663).

Contemporary use of lipid-lowering therapy for secondary prevention in Korean patients with atherosclerotic cardiovascular diseases

Background/Aims@#We evaluated the contemporary use of lipid-lowering therapy (LLT) in Korean patients with atherosclerotic cardiovascular disease (ASCVD), and identified factors associated with statin non-prescription. @*Methods@#Using the Korean Health Insurance Review and Assessment data, we identified LLT-naïve subjects newly diagnosed with ASCVD between 2011 and 2012, and followed up until 2015. LLT-naïve status was defined as no LLT prescription for 1 year before ASCVD diagnosis. ASCVD was defined as first hospitalization or emergency room visit for coronary artery disease (CAD), acute cerebrovascular disease (CVD), or peripheral artery disease (PAD). Statin intensity was defined per the 2013 American College of Cardiology/American Heart Association guideline for cholesterol treatment. @*Results@#The study enrolled 80,884 subjects newly diagnosed with ASCVD, of whom only 48,725 (60.2%) received LLT during the follow-up period. Statin, combination of statin and non-statin, and non-statin LLT were administered in 50.5%, 9.7%, and 0.1% of all subjects, respectively. Statins were prescribed to 80.4% of CAD patients but only to 50.2% and 46.8% of CVD and PAD patients. Statin-based LLT usually had moderate- (77.2%) or high-intensity (18.5%). Subjects not prescribed statins were younger or older (< 40 or ≥ 70 years), more commonly female, and more likely to have comorbidities. Statins were prescribed at the time of ASCVD diagnosis in 45.5% of all subjects, and in 53.0% within 90 days of diagnosis. @*Conclusions@#Only 60% of LLT-naïve Korean patients newly diagnosed with ASCVD received statins. Statins were often prescribed in subjects with CAD but less commonly in those with CVD or PAD. Moderate-intensity statins were most frequently used.

Update on Monogenic Diabetes in Korea

Monogenic diabetes, including maturity-onset diabetes of the young, neonatal diabetes, and other rare forms of diabetes, results from a single gene mutation. It has been estimated to represent around 1% to 6% of all diabetes. With the advances in genome sequencing technology, it is possible to diagnose more monogenic diabetes cases than ever before. In Korea, 11 studies have identified several monogenic diabetes cases, using Sanger sequencing and whole exome sequencing since 2001. The recent largest study, using targeted exome panel sequencing, found a molecular diagnosis rate of 21.1% for monogenic diabetes in clinically suspected patients. Mutations in glucokinase (GCK), hepatocyte nuclear factor 1α (HNF1A), and HNF4A were most commonly found. Genetic diagnosis of monogenic diabetes is important as it determines the therapeutic approach required for patients and helps to identify affected family members. However, there are still many challenges, which include a lack of simple clinical criterion for selecting patients for genetic testing, difficulties in interpreting the genetic test results, and high costs for genetic testing. In this review, we will discuss the latest updates on monogenic diabetes in Korea, and suggest an algorithm to screen patients for genetic testing. The genetic tests and non-genetic markers for accurate diagnosis of monogenic diabetes will be also reviewed.

Oral Glucose Tolerance Testing Allows Better Prediction of Diabetes in Women with a History of Gestational Diabetes Mellitus

BACKGROUND: We aimed to identify the postpartum metabolic factors that were associated with the development of diabetes in women with a history of gestational diabetes mellitus (GDM). In addition, we examined the role of the oral glucose tolerance test (OGTT) in the prediction of future diabetes. METHODS: We conducted a prospective study of 179 subjects who previously had GDM but did not have diabetes at 2 months postpartum. The initial postpartum examination including a 75-g OGTT and the frequently sampled intravenous glucose tolerance test (FSIVGTT) was performed 12 months after delivery, and annual follow-up visits were made thereafter. RESULTS: The insulinogenic index (IGI30) obtained from the OGTT was significantly correlated with the acute insulin response to glucose (AIRg) obtained from the FSIVGTT. The disposition indices obtained from the OGTT and FSIVGTT were also significantly correlated. Women who progressed to diabetes had a lower insulin secretory capacity including IGI30, AIRg, and disposition indices obtained from the FSIVGTT and OGTT compared with those who did not. However, the insulin sensitivity indices obtained from the OGTT and FSIVGTT did not differ between the two groups. Multivariate logistic regression analysis showed that the 2-hour glucose and disposition index obtained from the FSIVGTT were significant postpartum metabolic risk factors for the development of diabetes. CONCLUSION: We identified a crucial role of β-cell dysfunction in the development of diabetes in Korean women with previous GDM. The 2-hour glucose result from the OGTT is an independent predictor of future diabetes. Therefore, the OGTT is crucial for better prediction of future diabetes in Korean women with previous GDM.

Diabetes Fact Sheets in Korea, 2018: An Appraisal of Current Status

BACKGROUND: The objective of this study was to investigate the prevalence, management, and comorbidities of diabetes among Korean adults aged 30 years and older. METHODS: This study used 2013 to 2016 data from the Korea National Health and Nutrition Examination Survey, a nationally-representative survey of the Korean population. Diabetes was defined as fasting glucose ≥126 mg/dL, current use of antidiabetic medication, a previous history of diabetes, or glycosylated hemoglobin (HbA1c) ≥6.5%. RESULTS: In 2016, 14.4% (approximately 5.02 million) of Korean adults had diabetes. The prevalence of impaired fasting glucose was 25.3% (8.71 million). From 2013 to 2016, the awareness, control, and treatment rates for diabetes were 62.6%, 56.7%, and 25.1%, respectively. People with diabetes had the following comorbidities: obesity (50.4%), abdominal obesity (47.8%), hypertension (55.3%), and hypercholesterolemia (34.9%). The 25.1%, 68.4%, and 44.2% of people with diabetes achieved HbA1c <6.5%, blood pressure <140/85 mm Hg, and low density lipoprotein cholesterol <100 mg/dL. Only 8.4% of people with diabetes had good control of all three targets. CONCLUSION: This study confirms that diabetes is as an important public health problem. Efforts should be made to increase awareness, detection, and comprehensive management of diabetes to reduce diabetes-related morbidity and mortality.

2019 Clinical Practice Guidelines for Type 2 Diabetes Mellitus in Korea

The Committee of Clinical Practice Guidelines of the Korean Diabetes Association revised and updated the 6th Clinical Practice Guidelines in 2019. Targets of glycemic, blood pressure, and lipid control in type 2 diabetes mellitus (T2DM) were updated. The obese and overweight population is increasing steadily in Korea, and half of the Koreans with diabetes are obese. Evidence-based recommendations for weight-loss therapy for obesity management as treatment for hyperglycemia in T2DM were provided. In addition, evidence from large clinical studies assessing cardiovascular outcomes following the use of sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide 1 receptor agonists in patients with T2DM were incorporated into the recommendations.

Progression to Gestational Diabetes Mellitus in Pregnant Women with One Abnormal Value in Repeated Oral Glucose Tolerance Tests

BACKGROUND: Women with one abnormal value (OAV) in a 100 g oral glucose tolerance test (OGTT) during pregnancy are reported to have an increased risk of adverse pregnancy outcomes. However, there is limited data about whether women with OAV will progress to gestational diabetes mellitus (GDM) when the OGTT is repeated. METHODS: To identify clinical and metabolic predictors for GDM in women with OAV, we conducted a retrospective study and identified women with OAV in the OGTT done at 24 to 30 weeks gestational age (GA) and repeated the second OGTT between 32 and 34 weeks of GA. RESULTS: Among 137 women with OAV in the initial OGTT, 58 (42.3%) had normal, 40 (29.2%) had OAV and 39 (28.5%) had GDM in the second OGTT. Maternal age, prepregnancy body mass index, weight gain from prepregnancy to the second OGTT, GA at the time of the OGTT, and parity were similar among normal, OAV, and GDM groups. Plasma glucose levels in screening tests were different (151.8±15.7, 155.8±14.6, 162.5±20.3 mg/dL, P<0.05), but fasting, 1-, 2-, and 3-hour glucose levels in the initial OGTT were not. Compared to women with screen negative, women with untreated OAV had a higher frequency of macrosomia. CONCLUSION: We demonstrated that women with OAV in the initial OGTT significantly progressed to GDM in the second OGTT. Clinical parameters predicting progression to GDM were not found. Repeating the OGTT in women with OAV in the initial test may be helpful to detect GDM progression.

Metformin Ameliorates Lipotoxic β-Cell Dysfunction through a Concentration-Dependent Dual Mechanism of Action

BACKGROUND: Chronic exposure to elevated levels of free fatty acids contributes to pancreatic β-cell dysfunction. Although it is well known that metformin induces cellular energy depletion and a concomitant activation of AMP-activated protein kinase (AMPK) through inhibition of the respiratory chain, previous studies have shown inconsistent results with regard to the action of metformin on pancreatic β-cells. We therefore examined the effects of metformin on pancreatic β-cells under lipotoxic stress.METHODS: NIT-1 cells and mouse islets were exposed to palmitate and treated with 0.05 and 0.5 mM metformin. Cell viability, glucose-stimulated insulin secretion, cellular adenosine triphosphate, reactive oxygen species (ROS) levels and Rho kinase (ROCK) activities were measured. The phosphorylation of AMPK was evaluated by Western blot analysis and mRNA levels of endoplasmic reticulum (ER) stress markers and NADPH oxidase (NOX) were measured by real-time quantitative polymerase chain reaction analysis.RESULTS: We found that metformin has protective effects on palmitate-induced β-cell dysfunction. Metformin at a concentration of 0.05 mM inhibits NOX and suppresses the palmitate-induced elevation of ER stress markers and ROS levels in a AMPK-independent manner, whereas 0.5 mM metformin inhibits ROCK activity and activates AMPK.CONCLUSION: This study suggests that the action of metformin on β-cell lipotoxicity was implemented by different molecular pathways depending on its concentration. Metformin at a usual therapeutic dose is supposed to alleviate lipotoxic β-cell dysfunction through inhibition of oxidative stress and ER stress.

Independent Association of Serum Aldosterone Level with Metabolic Syndrome and Insulin Resistance in Korean Adults

BACKGROUND AND OBJECTIVES@#A relationship between renin-angiotensin system (RAS) components and metabolic syndrome (MetS) has been suggested, but not elucidated clearly. We examined the levels of RAS components in patients with and without MetS and their association with MetS in Korean population.@*METHODS@#This study was approved by the review boards of the participating institutions and endorsed by the Korean Society of Lipid and Atherosclerosis. We screened 892 Koreans aged ≥20 years who underwent evaluation of hypertension, diabetes, or dyslipidemia at 6 tertiary hospitals in 2015–2016. After excluding patients who were taking diuretics, β-blockers, or RAS blockers, or suspected of primary aldosteronism, 829 individuals were enrolled. Anthropometric and biochemical parameters including aldosterone, plasma renin activity (PRA), and aldosterone-to-PRA ratio were evaluated. The homeostasis model assessment for insulin resistance (HOMA-IR) were used for evaluating insulin resistance.@*RESULTS@#The mean age of the participants was 52.8±12.8 years, 56.3% were male, and their mean systolic and diastolic blood pressures were 133.9±20.0 and 81.2±14.6 mmHg, respectively. The levels of serum aldosterone, but not PRA, were significantly higher in subjects with MetS than in those without (20.6±33.6 vs. 15.3±12.2 ng/dL, p < 0.05), and positively correlated with waist circumference, blood pressure, triglycerides, and glycated hemoglobin. The levels of aldosterone were independently associated with the number of MetS components and HOMA-IR after adjusting for conventional risk factors.@*CONCLUSIONS@#Serum aldosterone levels were higher in Korean adults with MetS than in those without. This finding suggests that increased aldosterone level might be closely associated with insulin resistance.

Independent Association of Serum Aldosterone Level with Metabolic Syndrome and Insulin Resistance in Korean Adults

BACKGROUND AND OBJECTIVES: A relationship between renin-angiotensin system (RAS) components and metabolic syndrome (MetS) has been suggested, but not elucidated clearly. We examined the levels of RAS components in patients with and without MetS and their association with MetS in Korean population. METHODS: This study was approved by the review boards of the participating institutions and endorsed by the Korean Society of Lipid and Atherosclerosis. We screened 892 Koreans aged ≥20 years who underwent evaluation of hypertension, diabetes, or dyslipidemia at 6 tertiary hospitals in 2015–2016. After excluding patients who were taking diuretics, β-blockers, or RAS blockers, or suspected of primary aldosteronism, 829 individuals were enrolled. Anthropometric and biochemical parameters including aldosterone, plasma renin activity (PRA), and aldosterone-to-PRA ratio were evaluated. The homeostasis model assessment for insulin resistance (HOMA-IR) were used for evaluating insulin resistance. RESULTS: The mean age of the participants was 52.8±12.8 years, 56.3% were male, and their mean systolic and diastolic blood pressures were 133.9±20.0 and 81.2±14.6 mmHg, respectively. The levels of serum aldosterone, but not PRA, were significantly higher in subjects with MetS than in those without (20.6±33.6 vs. 15.3±12.2 ng/dL, p < 0.05), and positively correlated with waist circumference, blood pressure, triglycerides, and glycated hemoglobin. The levels of aldosterone were independently associated with the number of MetS components and HOMA-IR after adjusting for conventional risk factors. CONCLUSIONS: Serum aldosterone levels were higher in Korean adults with MetS than in those without. This finding suggests that increased aldosterone level might be closely associated with insulin resistance.

Screening, Diagnosis, and Treatment of Familial Hypercholesterolemia: Symposium of the Education Committee, Korean Society of Lipid and Atherosclerosis

Familial hypercholesterolemia (FH) is typically associated with single gene mutation that is inherited by autosomal dominant manner. Due to high cardiovascular risk, aggressive discovery, diagnosis, and treatment of FH are critical. Although FH is being increasingly spotlighted, we do not have sufficient data on Korean patients with FH. Here, we present the content of symposium of the Education Committee, Korean Society of Lipid and Atherosclerosis held in May 2018: 1) epidemiology, clinical diagnosis, Korean FH data, and regulation in Korea; 2) genes associated with FH, sequencing process in suspicious proband, cascade screening, and difficulty in genetic diagnosis in FH; 3) the importance of lipid-lowering therapy in FH, conventional and novel therapeutics for FH; 4) diagnosis of FH in children and adolescence, screening, and treatment of FH in children and adolescence; 5) history of FH studies in Korea, the structure and current status of FH registry of Korean Society of Lipid and Atherosclerosis; and 6) difficulty in diagnosis of heterozygous and homozygous FH, drug intolerance and achievement of treatment target. Discussion between speakers and panels were also added. We hope that this article is helpful for understanding FH and future studies performed in Korea.

Pathophysiology of Type 2 Diabetes in Koreans

The pathophysiology of type 2 diabetes is characterized by variable degrees of insulin resistance and impaired insulin secretion. Both genetic and environmental factors serve as etiologic factors. Recent genetic studies have identified at least 83 variants associated with diabetes. A significant number of these loci are thought to be involved in insulin secretion, either through β-cell development or β-cell dysfunction. Environmental factors have changed rapidly during the past half century, and the increased prevalence of obesity and diabetes can be attributed to these changes. Environmental factors may affect epigenetic changes and alter susceptibility to diabetes. A recent epidemiologic study revealed that Korean patients with type 2 diabetes already had impaired insulin secretion and insulin resistance 10 years before the onset of diabetes. Those who developed diabetes showed impaired β-cell compensation with an abrupt decrease in insulin secretion during the last 2 years before diabetes developed. The retrograde trajectory of the disposition index differed according to the baseline subgroups of insulin secretion and insulin sensitivity. We hope that obtaining a more detailed understanding of the perturbations in the major pathophysiologic process of diabetes on the individual level will eventually lead to the implementation of precision medicine and improved patient outcomes.

Application of the 2013 American College of Cardiology/American Heart Association Cholesterol Guideline to the Korean National Health and Nutrition Examination Surveys from 1998 to 2012

BACKGROUND: The 2013 American College of Cardiology/American Heart Association (ACC/AHA) guideline for the treatment of blood cholesterol recommends statin therapy for individuals at high risk of atherosclerotic cardiovascular disease (ASCVD). The aim of this study was to investigate serial trends in the percentages of Korean adults considered eligible for statin therapy according to the new ACC/AHA cholesterol guideline. METHODS: Data from the Korean National Health and Nutrition Examination Survey (KNHANES) I (1998, n=7,698), II (2001, n=5,654), III (2005, n=5,269), IV (2007 to 2009, n=15,727), and V (2010 to 2012, n=16,304), which used a stratified, multistage, probability sampling design, were used as representative of the entire Korean population. RESULTS: The percentage of adults eligible for statin therapy according to the ACC/AHA cholesterol guideline increased with time: 17.0%, 19.0%, 20.8%, 20.2%, and 22.0% in KNHANES I, II, III, IV, and V, respectively (P=0.022). The prevalence of ASCVD was 1.4% in KNHANES I and increased to 3.3% in KNHANES V. The percentage of diabetic patients aged 40 to 75 years with a low density lipoprotein cholesterol levels of 70 to 189 mg/dL increased from 4.8% in KNHANES I to 6.1% in KNHANES V. People with an estimated 10-year ASCVD risk ≥7.5% and aged 40 to 75 years accounted for the largest percentage among the four statin benefit groups: 9.1% in KNHANES I and 11.0% in KNHANES V. CONCLUSION: Application of the 2013 ACC/AHA guideline has found that the percentage of Korean adults in the statin benefit groups has increased over the past 15 years.

Findings of a 1303 Korean whole-exome sequencing study

Ethnically specific data on genetic variation are crucial for understanding human biology and for clinical interpretation of variant pathogenicity. We analyzed data obtained by deep sequencing 1303 Korean whole exomes; the data were generated by three independent whole exome sequencing projects (named the KOEX study). The primary focus of this study was to comprehensively analyze the variant statistics, investigate secondary findings that may have clinical actionability, and identify loci that should be cautiously interpreted for pathogenicity. A total of 495 729 unique variants were identified at exonic regions, including 169 380 nonsynonymous variants and 4356 frameshift insertion/deletions. Among these, 76 607 were novel coding variants. On average, each individual had 7136 nonsynonymous single-nucleotide variants and 74 frameshift insertion/deletions. We classified 13 pathogenic and 13 likely pathogenic variants in 56 genes that may have clinical actionability according to the guidelines of the American College of Medical Genetics and Genomics, and the Association for Molecular Pathology. The carrier frequency of these 26 variants was 2.46% (95% confidence interval 1.73–3.46). To identify loci that require cautious interpretation in clinical sequencing, we identified 18 genes that are prone to sequencing errors, and 671 genes that are highly polymorphic and carry excess nonsynonymous variants. The catalog of identified variants, its annotation and frequency information are publicly available (https://koex.snu.ac.kr). These findings should be useful resources for investigating ethnically specific characteristics in human health and disease.

Erratum: Correction of Figure: Clinical Implications of Various Criteria for the Biochemical Diagnosis of Insulinoma

In the original article, the legend of Fig. 1 was incorrect. The solid line was noninsulinoma, and the dotted line was insulinoma.