Jeong-Taek Woo

Background: This study evaluated the 6-month effects of the Korean Diabetes Prevention Study (KDPS) interventions on body weight and cardiometabolic parameters in adults with prediabetes.Methods: Adults aged 30–70 years with body mass index ≥23 kg/m² were randomized to lifestyle modification (LSM), metformin (MET), or standard management (STM). The KDPS-LSM program combined intensive nutrition education and LSM including 10 key healthy habits with personalized counseling, targeting ≥5% weight loss in 6 months followed by long-term maintenance. Cardiometabolic parameters were assessed before and after the intervention (Trial registration: CRIS KCT0002260, NCT02981121).Results: Of 701 completers (262 STM, 222 LSM, 217 MET), all groups showed significant weight reduction (−0.7 kg STM, −2.3 kg LSM, −2.0 kg MET; P<0.001). The LSM group achieved the largest weight reduction and the highest ≥5% weight-loss rate. Glycemic indices remained largely stable in the LSM and MET groups, whereas FPG increased significantly in the STM group; a significant reduction in HbA1c was observed only in the MET group. Even modest (<5%) weight loss conferred cardiometabolic benefits, and greater loss correlated with higher adherence to LSM or higher MET exposure.Conclusion: All KDPS interventions reduced body weight after 6 months, with LSM providing the best weight outcomes and MET showing the most favorable glycemic effects.

We present Korea10K, the largest genomic dataset of the Korean population, comprising 10,239 high-coverage whole genomes (mean depth 30×) with matched multiomic profiles and phenotype data. Korea10K achieves complete and near-complete discovery of very rare and ultra-rare alleles, respectively, at 9,000 Korean genomes. This dataset provides the high-quality population-specific imputation panel, enabling accurate inference of low-frequency variants. Admixture analyses confirm the genetic homogeneity of the Korean population, despite its diverse Y-chromosomal, mitochondrial, and HLA repertoires. This pattern reflects a long and continuous lineage history characterized by persistent internal admixture and genomic homogenization over thousands of years on the Korean peninsula. We also identified 16.8 million genomic variants that directly modify CG sites by creating or abolishing CG dinucleotides, providing the population-scale evidence of coordinated genomic-epigenomic regulatory mechanism in Koreans.

The effect of diabetes distress on glycemic control and its association with diabetes complications is still poorly understood. We aimed to study the clinical features of patients with high diabetes distress, focusing on changes in glycemic control and risk of diabetic complications. From the Korean National Diabetes Program data, we investigated 1862 individuals with type 2 diabetes mellitus (T2DM) who completed diabetic complication studies and the Korean version of the Problem Areas in Diabetes Survey (PAID-K). A total score of PAID-K ≥ 40 was considered indicative of high distress. Individuals with high distress (n = 589) had significantly higher levels of glycated hemoglobin than those without distress (7.4% vs. 7.1%, p < 0.001). This trend persisted throughout the 3-year follow-up period. Higher PAID-K scores were associated with younger age, female gender, longer duration of diabetes, and higher carbohydrate intake (all p < 0.05). There was a significant association between high distress and diabetic neuropathy (adjusted odds ratio, 1.63; p = 0.002), but no significant association was found with other complications, including retinopathy, albuminuria, and carotid artery plaque. In conclusion, high diabetes distress was associated with uncontrolled hyperglycemia and higher odds of having diabetic neuropathy.

Few studies have investigated the association between smoking and microvascular complications in the Asian population with type 2 diabetes mellitus (T2DM). We aimed to investigate the relationship between smoking status and microvascular complications in Korean patients with T2DM. From the Korean National Diabetes Program cohort, we included 2316 Korean male with T2DM who had baseline clinical information available, including their smoking status, and underwent diabetic complication studies. Compared to non-smokers, current smokers had higher odds of any-microvascular complications [adjusted odds ratio (aOR) 1.45, 95% confidence interval (CI) 1.07–1.97, p=0.016]. The odds of neuropathy were significantly higher; however, the odds of retinopathy were significantly lower in current smokers than in nonsmokers (all p<0.05). Among those who underwent repeated complication tests after 3 years, the risk of newly developed retinopathy was significantly increased in ex-smokers [aOR 3.77 (95% CI 1.61–8.87), p=0.002]. Within ex-smokers, long smoking duration and smoking cessation within the recent 5 years were associated with an increased risk of newly developed retinopathy (all p<0.05). Male smokers had higher odds of having overall diabetic microvascular complications, including neuropathy. However, the odds of having retinopathy were significantly lower among current smokers. More attention and research are needed regarding the increased risk of retinopathy development in ex-smokers who have recently stopped smoking after a long history of smoking.

To investigate the pathophysiologic characteristics of diabetic complications, we identified differences in plasma metabolites in subjects with type 2 diabetes (T2DM) with or without diabetic macular edema (DME) and a disease duration > 15 years. An cohort of older T2DM patients with prolonged disease duration was established, and clinical information and biospecimens were collected following the guidelines of the National Biobank of Korea. DME phenotypes were identified by ophthalmologic specialists. For metabolomics studies, propensity matched case and control samples were selected. To discover multi-biomarkers in plasma, non-targeted metabolite profiling and oxylipin profiling in the discovery cohort were validated in an extended cohort. From metabolomic studies, 5 amino acids (asparagine, aspartic acid, glutamic acid, cysteine, and lysine), 2 organic compounds (citric acid and uric acid) and 4 oxylipins (12-oxoETE, 15-oxoETE, 9-oxoODE, 20-carboxy leukotriene B4) were identified as candidate multi-biomarkers which can guide DME diagnosis among non-DME subjects. Receiver operating characteristic curves revealed high diagnostic value of the combined 5 amino acids and 2 organic compounds (AUC = 0.918), and of the 4 combined oxylipins (AUC = 0.957). Our study suggests that multi-biomarkers may be useful for predicting DME in older T2DM patients.

Objective: To investigate the pathophysiologic characteristics of diabetic complications, we identified differences in plasma metabolites in subjects with type 2 diabetes (T2DM) with or without diabetic macular edema (DME) and a disease duration > 15 yrs.Subjects and Methods: An elderly cohort of T2DM patients with prolonged disease duration was established, and clinical information and biospecimens were collected following the guidelines of the National Biobank of Korea. DME phenotypes were identified by ophthalmologic specialists. For metabolomics studies, propensity matched case and control samples were selected. To discover multi-biomarkers in plasma, non-targeted metabolite profiling and oxylipin profiling in the discovery cohort were validated in an extended cohort.Results: From metabolomic studies, 5 amino acids (asparagine, aspartic acid, glutamic acid, cysteine, and lysine), 2 organic compounds (citric acid and uric acid) and 4 oxylipins (12-oxoETE, 15-oxoETE, 9-oxoODE, 20-carboxy leukotriene B4) were identified as candidate multi-biomarkers which can guide DME diagnosis among non-DME subjects. Receiver operating characteristic curves revealed high diagnostic value of the combined 5 amino acids and 2 organic compounds (AUC = 0.918), and of the 4 combined oxylipins (AUC = 0.957).Conclusions: Our study suggests that multi-biomarkers may be useful for predicting DME in elderly T2DM patients.

Background/Aims. This study was designed to identify the clinical characteristics of Korean patients with type 2 diabetes according to metformin use. Methods. This cross-sectional study based on the Korean National Diabetes Program 2 registry used its baseline clinical data collected from seven participating university hospitals in Korea. Patients with no significant changes in their oral hypoglycemic agents and no diabetes-related complications within the year prior to participation were enrolled. Patients’ clinical characteristics according to metformin use were analyzed. Results. Among 858 subjects included in the analyses, 706 were metformin users and 152 were nonmetformin users. Metformin users were significantly younger and had higher and glycated hemoglobin with significantly lower rates of accompanying microvascular complications such as retinopathy, cataracts, overt proteinuria, renal insufficiency, and peripheral neuropathy than nonusers. Meanwhile, there was a significantly lower prevalence of malignancy and depression among metformin users. These associations remained significant in multivariate analyses. The prevalence rate of macrovascular complications was not significantly different between the two groups. Conclusions. There were significant differences with respect to clinical characteristics and comorbidity prevalence according to metformin use among Korean type 2 diabetes patients. Long-term follow-up of these patients is necessary to observe how this difference will affect clinical outcomes for these patients.

Background: The primary aim of this study was to assess the utility of fasting plasma glucose (FPG) and HbA1c to identify diabetes by the 2‐hour plasma glucose (PG) criterion in the Korean population at high risk for diabetes.Methods: A total of 1646 participants with a body mass index of ≥23 kg/m² without having a history of diabetes were recruited in this study. The cut‐off values of FPG and HbA1c for detecting diabetes were identified using the Youden index using receiver operating characteristic (ROC) analysis. The gold standard for diabetes prediction was defined by the 2‐hour PG level of ≥200 mg/dL.Results: The participants comprised 54.0% women, and the mean age of all participants was 55.0 ± 8.1 years. At baseline, FPG was 104.1 ± 14.2 mg/dL, the 2‐hour PG value was 162.9 ± 55.3 mg/dL, and HbA1c was 5.9% ± 0.5%. Four hundred and forty‐six subjects (27.1%) were diagnosed with diabetes and 976 subjects (59.3%) were determined to be at prediabetes. The area under the ROC curve (AUC) of FPG and HbA1c for diabetes were 0.776 and 0.802, while the AUC of FPG and HbA1c for prediabetes were 0.515 and 0.477. The optimal cut‐off value for diagnosing diabetes of FPG and HbA1c were 104.5 mg/dL (sensitivity 75.8%, specificity 67.5%) and 5.9% (sensitivity 80.6%, specificity 63.8%), respectively.Conclusions: FPG of 104.5 mg/dL and HbA1c value of 5.9% (41 mmol/mol) can be used as an optimal screening value for diabetes by 2‐hour PG criterion in the Korean population at high risk for diabetes.

There have been equivocal results in studies of the effects of dipeptidyl peptidase-4 inhibitors (DPP-4i) on fractures. In this study, we analyzed the effect of DPP-4i on bone fracture risk in a Korean population. We extracted subjects (n = 11,164) aged 50 years or older from the National Health Insurance Service-National Sample Cohort 2.0 from 2009 to 2014. Our control group included subjects without diabetes (n = 5,582), and our treatment groups with diabetes included DPP-4i users (n = 1,410) and DPP-4i non-users (n = 4,172). The primary endpoint was the incidence of a composite outcome consisting of osteoporosis diagnosis, osteoporotic fractures, vertebral fractures, non-vertebral fractures, and femoral fractures. The secondary endpoint was the incidence of each individual component of the composite outcome. Survival analysis was performed with adjustment for age, gender, diabetes complications severity index, Charlson comorbidity index, hypertension medication, and dyslipidemia treatment. The incidence of the composite outcome per 1,000 person-years was 0.089 in DPP-4i users, 0.099 in DPP-4i non-users, and 0.095 in controls. There was no significant difference in fracture risk between DPP-4i users and DPP-4i non-users or controls after the adjustments (P > 0.05). The incidences of osteoporosis diagnosis, osteoporotic fractures, vertebral fractures, non-vertebral fractures, and femoral fractures were not significantly different between DPP-4i users and non-users. The results of subgroup analyses by gender and age were consistent. DPP-4i had no significant effect on the risk of fractures in a Korean population.

Rhee SY, et al. Diabetes Metab J. 2018 Jan;42:e41. https://doi.org/10.4093/dmj.2018.0033