Using Nanoscopic Solvent Defects for the Spatial and Temporal Manipulation of Single Assemblies of Molecules.

Here we report the use of defects in ordered solvents to form, manipulate, and characterize individual molecular assemblies of either small-molecule amphiphiles or polymers. The approach exploits nanoscopic control of the structure of nematic solvents (achieved by the introduction of topological defects) to trigger the formation of molecular assemblies and the subsequent manipulation of defects using electric fields. We show that molecular assemblies formed in solvent defects slow defect motion in the presence of an electric field and that time-of-flight measurements correlate with assembly size, suggesting methods for the characterization of single assemblies of molecules. Solvent defects are also used to transport single assemblies of molecules between solvent locations that differ in composition, enabling the assembly and disassembly of molecular "nanocontainers". Overall, our results provide new methods for studying molecular self-assembly at the single-assembly level and new principles for integrated nanoscale chemical systems that use solvent defects to transport and position molecular cargo.

Using machine learning and liquid crystal droplets to identify and quantify endotoxins from different bacterial species.

Detection and quantification of bacterial endotoxins is important in a range of health-related contexts, including during pharmaceutical manufacturing of therapeutic proteins and vaccines. Here we combine experimental measurements based on nematic liquid crystalline droplets and machine learning methods to show that it is possible to classify bacterial sources (Escherichia coli, Pseudomonas aeruginosa, Salmonella minnesota) and quantify concentration of endotoxin derived from all three bacterial species present in aqueous solution. The approach uses flow cytometry to quantify, in a high-throughput manner, changes in the internal ordering of micrometer-sized droplets of nematic 4-cyano-4'-pentylbiphenyl triggered by the endotoxins. The changes in internal ordering alter the intensities of light side-scattered (SSC, large-angle) and forward-scattered (FSC, small-angle) by the liquid crystal droplets. A convolutional neural network (Endonet) is trained using the large data sets generated by flow cytometry and shown to predict endotoxin source and concentration directly from the FSC/SSC scatter plots. By using saliency maps, we reveal how EndoNet captures subtle differences in scatter fields to enable classification of bacterial source and quantification of endotoxin concentration over a range that spans eight orders of magnitude (0.01 pg mL-1 to 1 µg mL-1). We attribute changes in scatter fields with bacterial origin of endotoxin, as detected by EndoNet, to the distinct molecular structures of the lipid A domains of the endotoxins derived from the three bacteria. Overall, we conclude that the combination of liquid crystal droplets and EndoNet provides the basis of a promising analytical approach for endotoxins that does not require use of complex biologically-derived reagents (e.g., Limulus amoebocyte lysate).

Soft matter from liquid crystals.

Liquid crystals (LCs) are fluids within which molecules exhibit long-range orientational order, leading to anisotropic properties such as optical birefringence and curvature elasticity. Because the ordering of molecules within LCs can be altered by weak external stimuli, LCs have been widely used to create soft matter systems that respond optically to electric fields (LC display), temperature (LC thermometer) or molecular adsorbates (LC chemical sensor). More recent studies, however, have moved beyond investigations of optical responses of LCs to explore the design of complex LC-based soft matter systems that offer the potential to realize more sophisticated functions (e.g., autonomous, self-regulating chemical responses to mechanical stimuli) by directing the interactions of small molecules, synthetic colloids and living cells dispersed within the bulk of LCs or at their interfaces. These studies are also increasingly focusing on LC systems driven beyond equilibrium states. This review presents one perspective on these advances, with an emphasis on the discovery of fundamental phenomena that may enable new technologies. Three areas of progress are highlighted; (i) directed assembly of amphiphilic molecules either within topological defects of LCs or at aqueous interfaces of LCs, (ii) templated polymerization in LCs via chemical vapor deposition, an approach that overcomes fundamental challenges related to control of LC phase behavior during polymerization, and (iii) studies of colloids in LCs, including chiral colloids, soft colloids that are strained by LCs, and active colloids that are driven into organized states by dissipation of energy (e.g. bacteria). These examples, and key unresolved issues discussed at the end of this perspective, serve to convey the message that soft matter systems that integrate ideas from LC, surfactant, polymer and colloid sciences define fertile territory for fundamental studies and creation of future transformative technologies.

Influence of interface stabilisers and surrounding aqueous phases on nematic liquid crystal shells.

We investigate the nematic-isotropic (N-I) transition in shells of the liquid crystal 5CB, surrounded by aqueous phases that conventionally are considered to be immiscible with 5CB. The aqueous phases contain either sodium dodecyl sulfate (SDS) or polyvinyl alcohol (PVA) as stabiliser, the former additionally promoting homeotropic director alignment. For all shell configurations we find a depression of the clearing point compared to pure 5CB, indicating that a non-negligible fraction of the constituents of the surrounding phases enter the shell, predominantly water. In hybrid-aligned shells, with planar outer and homeotropic inner boundary (or vice versa), the N-I transition splits into two steps, with a consequent three-step textural transformation. We explain this as a result of the order-enhancing effect of a monolayer of radially aligned SDS molecules adsorbed at the homeotropic interface.

Phosphoinositide dependent protein kinase 1 is required for exercise-induced cardiac hypertrophy but not the associated mitochondrial adaptations.

Phosphoinositide-dependent protein kinase-1 (PDPK1) is an important mediator of phosphatidylinositol 3-kinase (PI3K) signaling. We previously reported that PI3K but not Akt signaling mediates the increase in mitochondrial oxidative capacity following physiological cardiac hypertrophy. To determine if PDPK1 regulates these metabolic adaptations we examined mice with cardiomyocyte-specific heterozygous knockout of PDPK1 (cPDPK1(+/-)) after 5 wk. exercise swim training. Akt phosphorylation at Thr308 increased by 43% in wildtype (WT) mice but not in cPDPK1(+/-) mice following exercise training. Ventricular contractile function was not different between WT and cPDPK1(+/-) mice at baseline. In addition, exercise did not influence ventricular function in WT or cPDPK1(+/-) mice. Heart weight normalized to tibia length ratios increased by 13.8% in WT mice (6.2±0.2 vs. 7.1±0.2, P=0.001), but not in cPDPK1(+/-) (6.2±0.3 vs. 6.5±0.2, P=0.20) mice after swim training. Diastolic LV dimension increased in WT mice (3.7±0.1 vs. 4.0±0.1 mm, P=0.01) but not in cPDPK1(+/-) (3.8±0.1 vs. 3.7±0.1 mm, P=0.56) following swim training. Maximal mitochondrial oxygen consumption (VADP, nmol/min/mg) using palmitoyl carnitine as a substrate was significantly increased in mice of all genotypes following swim training (WT: 13.6±0.6 vs.16.1±0.9, P=0.04; cPDPK1(+/-): 12.4±0.6 vs.15.9±1.2, P=0.04). These findings suggest that PDPK1 is required for exercise-induced cardiac hypertrophy but does not contribute to exercise-induced increases in mitochondrial function.

Macroscopic control of helix orientation in films dried from cholesteric liquid-crystalline cellulose nanocrystal suspensions.

The intrinsic ability of cellulose nanocrystals (CNCs) to self-organize into films and bulk materials with helical order in a cholesteric liquid crystal is scientifically intriguing and potentially important for the production of renewable multifunctional materials with attractive optical properties. A major obstacle, however, has been the lack of control of helix direction, which results in a defect-rich, mosaic-like domain structure. Herein, a method for guiding the helix during film formation is introduced, which yields dramatically improved uniformity, as confirmed by using polarizing optical and scanning electron microscopy. By raising the CNC concentration in the initial suspension to the fully liquid crystalline range, a vertical helix orientation is promoted, as directed by the macroscopic phase boundaries. Further control of the helix orientation is achieved by subjecting the suspension to a circular shear flow during drying.

A density functional theory investigation of the electronic structure and spin moments of magnetite.

We present the results of density functional theory (DFT) calculations on magnetite, Fe3O4, which has been recently considered as electrode in the emerging field of organic spintronics. Given the nature of the potential applications, we evaluated the magnetite room-temperature cubic [Formula: see text] phase in terms of structural, electronic, and magnetic properties. We considered GGA (PBE), GGA + U (PBE + U), and range-separated hybrid (HSE06 and HSE(15%)) functionals. Calculations using HSE06 and HSE(15%) functionals underline the impact that inclusion of exact exchange has on the electronic structure. While the modulation of the band gap with exact exchange has been seen in numerous situations, the dramatic change in the valence band nature and states near the Fermi level has major implications for even a qualitative interpretation of the DFT results. We find that HSE06 leads to highly localized states below the Fermi level while HSE(15%) and PBE + U result in delocalized states around the Fermi level. The significant differences in local magnetic moments and atomic charges indicate that describing room-temperature bulk materials, surfaces and interfaces may require different functionals than their low-temperature counterparts.

Cholesteric Spherical Reflectors with Tunable Color from Single-Domain Cellulose Nanocrystal Microshells.

The wavelength- and polarization-selective Bragg reflection of visible light exhibited by films produced by drying cholesteric liquid crystal (CLC) suspensions of cellulose nanocrystals (CNCs) render these biosourced nanoparticles highly potent for many optical applications. While the conventionally produced films are flat, the CLC-derived helical CNC arrangement would acquire new powerful features if given spherical curvature. Drying CNC suspension droplets does not work, because the onset of kinetic arrest in droplets of anisotropic colloids leads to severe buckling and loss of spherical shape. Here, these problems are avoided by confining the CNC suspension in a spherical microshell surrounding an incompressible oil droplet. This prevents buckling, ensures strong helix pitch compression, and produces single-domain cholesteric spherical reflector particles with distinct visible color. Interestingly, the constrained shrinkage leads to spontaneous puncturing, leaving every particle with a single hole through which the inner oil phase can be extracted for recycling. By mixing two different CNC types at varying fractions, the retroreflection color is tuned throughout the visible spectrum. The new approach adds a versatile tool in the quest to utilize bioderived CLCs, enabling spherically curved particles with the same excellent optical quality and smooth surface as previously obtained only in flat films.

Real-World Treatment Patterns according to Clinical Practice Guidelines in Patients with Type 2 Diabetes Mellitus and Established Cardiovascular Disease in Korea: Multicenter, Retrospective, Observational Study.

BACKGRUOUND: Recent diabetes management guidelines recommend that sodium-glucose cotransporter 2 inhibitors (SGLT2is) or glucagon-like peptide 1 receptor agonists (GLP-1RAs) with proven cardiovascular benefits should be prioritized for combination therapy in patients with type 2 diabetes mellitus (T2DM) and established cardiovascular disease (CVD). This study was aimed at evaluating SGLT2i or GLP-1RA usage rates and various related factors in patients with T2DM and established CVD. METHODS: We enrolled adults with T2DM aged ≥30 years who were hospitalized due to established CVD from January 2019 to May 2020 at 13 secondary and tertiary hospitals in Korea in this retrospective observational study. RESULTS: Overall, 2,050 patients were eligible for analysis among 2,107 enrolled patients. The mean patient age, diabetes duration, and glycosylated hemoglobin level were 70.0 years, 12.0 years, and 7.5%, respectively. During the mean follow-up duration of 9.7 months, 25.7% of the patients were prescribed SGLT2is after CVD events. However, only 1.8% were prescribed GLP-1RAs. Compared with SGLT2i non-users, SGLT2i users were more frequently male and obese. Furthermore, they had a shorter diabetes duration but showed worse glycemic control and better renal function at the time of the event. GLP-1RA users had a longer duration of diabetes and worse glycemic control at the time of the event than GLP-1RA non-users. CONCLUSION: The SGLT2i or GLP-1RA prescription rates were suboptimal in patients with T2DM and established CVD. Sex, body mass index, diabetes duration, glycemic control, and renal function were associated with the use of these agents.

Evaluation and Management of Patients with Diabetes and Heart Failure: A Korean Diabetes Association and Korean Society of Heart Failure Consensus Statement.

Diabetes mellitus is a major risk factor for the development of heart failure. Furthermore, the prognosis of heart failure is worse in patients with diabetes mellitus than in those without it. Therefore, early diagnosis and proper management of heart failure in patients with diabetes mellitus are important. This review discusses the current criteria for diagnosis and screening tools for heart failure and the currently recommended pharmacological therapies for heart failure. We also highlight the effects of anti-diabetic medications on heart failure.

Evaluation and Management of Patients With Diabetes and Heart Failure: A Korean Diabetes Association and Korean Society of Heart Failure Consensus Statement.

Diabetes mellitus is a major risk factor for the development of heart failure. Furthermore, the prognosis of heart failure is worse in patients with diabetes mellitus than in those without it. Therefore, early diagnosis and proper management of heart failure in patients with diabetes mellitus are important. This review discusses the current criteria for diagnosis and screening tools for heart failure and the currently recommended pharmacological therapies for heart failure. We also highlight the effects of anti-diabetic medications on heart failure.

Cardiovascular Outcomes according to Comorbidities and Low-Density Lipoprotein Cholesterol in Korean People with Type 2 Diabetes Mellitus.

BACKGROUND: There are no clear data to support the cardiovascular (CV) risk categories and low-density lipoprotein cholesterol (LDL-C) treatment goals in Korean people with type 2 diabetes mellitus (T2DM). We evaluated the incidence of cardiovascular disease (CVD) according to comorbidities and suggested LDL-C treatment goals in Korean people with T2DM in nationwide cohort data. METHODS: Using the Korean National Health Insurance Service database, 248,002 people aged 30 to 90 years with T2DM who underwent routine health check-ups during 2009 were included. Subjects with previous CVD were excluded from the study. The primary outcome was incident CVD, defined as a composite of myocardial infarction and ischemic stroke during the follow-up period from 2009 to 2018. RESULTS: The mean age of the study participants was 59.6±10.9 years, and median follow-up period was 9.3 years. CVD incidence increased in the order of DM duration of 5 years or more (12.04/1,000 person-years), hypertension (HT) (12.27/1,000 personyears), three or more CV risk factors (14.10/1,000 person-years), and chronic kidney disease (18.28/1,000 person-years). The risk of incident CVD increased linearly from an LDL-C level of ≥70 mg/dL in most patients with T2DM. In T2DM patients without HT or with a DM duration of less than 5 years, the CVD incidence increased from LDL-C level of ≥100 mg/dL. CONCLUSION: For primary prevention of CVD in Korean adults with T2DM, it can be helpful to lower LDL-C targets when there are chronic kidney disease, HT, a long duration of diabetes mellitus, or three or more CV risk factors.

Association between Low-Density Lipoprotein Cholesterol Level and Cardiovascular Outcomes in Korean Adults: A Nationwide Cohort Study.

BACKGROUND: To validate the treatment target of low-density lipoprotein cholesterol (LDL-C) level according to the cardiovascular disease (CVD) risk which was recommended by Korean dyslipidemia guideline. METHODS: We used the Korean National Health Insurance Service database which included 3,958,048 people aged 20 to 89 years who underwent regular health screening. The primary outcome was incident CVD, defined as a composite of myocardial infarction and stroke during the follow-up period from 2009 to 2018. RESULTS: The risk of CVD increased from LDL-C level of 70 mg/dL in very high-risk and high-risk groups and from 130 mg/dL in moderate-risk and low-risk groups. Adjusted hazard ratios (HRs) of LDL-C ranges 70-99, 100-129, 130-159, 160-189, and ≥190 mg/dL were 1.20 (95% confidence interval [CI], 1.08-1.33), 1.27 (1.15-1.42), 1.39 (1.23-1.56), 1.69 (1.45-1.96), and 1.84 (1.49- 2.27) in very high-risk group, and 1.07 (1.02-1.13), 1.16 (1.10-1.21), 1.29 (1.22-1.36), 1.45 (1.36-1.55), and 1.73 (1.58-1.90) in high-risk group. Adjusted HRs (95% CI) of LDL-C ranges 130-159, 160-189, and ≥190 mg/dL were 1.15 (1.11-1.20), 1.28 (1.22- 1.34), and 1.45 (1.36-1.54) in moderate-risk group and 1.07 (1.02-1.13), 1.20 (1.13-1.26), and 1.47 (1.37-1.57) in low-risk group. CONCLUSION: We confirmed the incidence of CVD was increased in higher LDL-C range. The risk of CVD increased from ≥70 mg/dL of LDL-C in very high-risk and high-risk groups, and from ≥130 mg/dL of LDL-C in moderate-risk and low-risk groups in Korean adults.

2023 Clinical Practice Guidelines for Diabetes Mellitus of the Korean Diabetes Association.

In May 2023, the Committee of Clinical Practice Guidelines of the Korean Diabetes Association published the revised clinical practice guidelines for Korean adults with diabetes and prediabetes. We incorporated the latest clinical research findings through a comprehensive systematic literature review and applied them in a manner suitable for the Korean population. These guidelines are designed for all healthcare providers nationwide, including physicians, diabetes experts, and certified diabetes educators who manage patients with diabetes or individuals at risk of developing diabetes. Based on recent changes in international guidelines and the results of a Korean epidemiological study, the recommended age for diabetes screening has been lowered. In collaboration with the relevant Korean medical societies, recently revised guidelines for managing hypertension and dyslipidemia in patients with diabetes have been incorporated into this guideline. An abridgment containing practical information on patient education and systematic management in the clinic was published separately.

The angiotensin receptor blocker and PPAR-γ agonist, telmisartan, delays inactivation of voltage-gated sodium channel in rat heart: novel mechanism of drug action.

Telmisartan is an angiotensin II receptor blocker and partial peroxisome proliferator-activated receptor gamma agonist that modulates the renin-angiotensin-aldosterone system. It is used primarily to manage hypertension, diabetic nephropathy, and congestive heart failure. Recent studies have reported that myocardial infarction (MI) has occurred in telmisartan-treated patients. The purpose of the study was to investigate the specific conditions and underlying mechanisms that may result in telmisartan-induced MI. We evaluated the effect of telmisartan on whole hearts, cardiomyocytes, and cardiac sarcolemmal ion channels. Hearts of 8-week-old male Sprague-Dawley rats were perfused with 3, 10, 30, or 100 µM telmisartan or losartan or with normal Tyrode's solution (control) for 3 h. We found that telmisartan induced myocardial infarction, with an infarct size of 21 % of the total at 30 µM (P < 0.0001) and 63 % of the total area at 100 µM (P < 0.001). Telmisartan also induced cardiac dysfunction (e.g., decreased heart rate, diminished coronary flow, hypercontracture, and arrhythmia). Confocal microscopy demonstrated that 30 µM telmisartan significantly elevated the intracellular Ca(2+) level, leading to hypercontracture and cell death. Patch clamp analysis of isolated cardiomyocytes revealed that telmisartan induced Na(+) overload by slowing the inactivation of voltage-gated Na(+) current (I (Na)), activating the reverse mode of Na(+)-Ca(2+) exchanger activity, and causing Ca(2+) overload. Telmisartan significantly delayed the inactivation of the voltage-gated Na(+) channel, causing cytosolic Na(+) overload, prolonged action potential duration, and subsequent Ca(2+) overload. Above 30 µM, telmisartan may potentially cause cardiac cell death and MI.

A Real-World Study of Long-Term Safety and Efficacy of Lobeglitazone in Korean Patients with Type 2 Diabetes Mellitus.

BACKGROUND: Thiazolidinediones (TZDs) have been associated with various safety concerns including weight gain, bladder cancer, and congestive heart failure (CHF). This study evaluated the efficacy and safety of lobeglitazone, a novel TZD in patients with type 2 diabetes mellitus (T2DM) in real practice. METHODS: In this non-interventional, multi-center, retrospective, and observational study conducted at 15 tertiary or secondary referral hospitals in Korea, a total of 2,228 patients with T2DM who received lobeglitazone 0.5 mg for more than 1 year were enrolled. RESULTS: Overall adverse events (AEs) occurred in 381 patients (17.10%) including edema in 1.97% (n=44). Cerebrovascular and cardiovascular diseases were identified in 0.81% (n=18) and 0.81% (n=18), respectively. One case of CHF was reported as an AE. Edema occurred in 1.97% (n=44) of patients. Hypoglycemia occurred in 2.47% (n=55) of patients. Fracture occurred in 1.17% (n=26) of all patients. Lobeglitazone significantly decreased HbA1c level, resulting in a mean treatment difference of -1.05%± 1.35% (P<0.001), and decreased total cholesterol, triglyceride, and low-density lipoprotein cholesterol. However, it increased high-density lipoprotein cholesterol, regardless of statin administration. The patients who received lobeglitazone 0.5 mg showed an apparent reduction in glycosylated hemoglobin (HbA1c) from baseline during the first 6 months of treatment. The HbA1c levels remained stable between months 6 and 42. CONCLUSION: Lobeglitazone has long-term safety profile, good glycemic-lowering effect and long-term durability of glycemic control in real-world clinical settings.

Current Status of Low-Density Lipoprotein Cholesterol Target Achievement in Patients with Type 2 Diabetes Mellitus in Korea Compared with Recent Guidelines.

BACKGROUND: We evaluated the achievement of low-density lipoprotein cholesterol (LDL-C) targets in patients with type 2 diabetes mellitus (T2DM) according to up-to-date Korean Diabetes Association (KDA), European Society of Cardiology (ESC)/European Atherosclerosis Society (EAS), and American Diabetes Association (ADA) guidelines. METHODS: This retrospective cohort study collected electronic medical record data from patients with T2DM (≥20 years) managed by endocrinologists from 15 hospitals in Korea (January to December 2019). Patients were categorized according to guidelines to assess LDL-C target achievement. KDA (2019): Very High-I (atherosclerotic cardiovascular disease [ASCVD]) <70 mg/dL; Very High-II (target organ damage [TOD], or cardiovascular risk factors [CVRFs]) <70 mg/dL; high (others) <100 mg/dL. ESC/EAS (2019): Very High-I (ASCVD): <55 mg/dL; Very High-II (TOD or ≥3-CVRF) <55 mg/dL; high (diabetes ≥10 years without TOD plus any CVRF) <70 mg/dL; moderate (diabetes <10 years without CVRF) <100 mg/dL. ADA (2019): Very High-I (ASCVD); Very High-II (age ≥40+ TOD, or any CVRF), for high intensity statin or statin combined with ezetimibe. RESULTS: Among 2,000 T2DM patients (mean age 62.6 years; male 55.9%; mean glycosylated hemoglobin 7.2%) ASCVD prevalence was 24.7%. Of 1,455 (72.8%) patients treated with statins, 73.9% received monotherapy. According to KDA guidelines, LDL-C target achievement rates were 55.2% in Very High-I and 34.9% in Very High-II patients. With ESC/EAS guidelines, target attainment rates were 26.6% in Very High-I, 15.7% in Very High-II, and 25.9% in high risk patients. Based on ADA guidelines, most patients (78.9%) were very-high risk; however, only 15.5% received high-intensity statin or combination therapy. CONCLUSION: According to current dyslipidemia management guidelines, LDL-C goal achievement remains suboptimal in Korean patients with T2DM.

2021 Clinical Practice Guidelines for Diabetes Mellitus of the Korean Diabetes Association.

The Committee of Clinical Practice Guidelines of the Korean Diabetes Association (KDA) updated the previous clinical practice guidelines for Korean adults with diabetes and prediabetes and published the seventh edition in May 2021. We performed a comprehensive systematic review of recent clinical trials and evidence that could be applicable in real-world practice and suitable for the Korean population. The guideline is provided for all healthcare providers including physicians, diabetes experts, and certified diabetes educators across the country who manage patients with diabetes or the individuals at the risk of developing diabetes mellitus. The recommendations for screening diabetes and glucose-lowering agents have been revised and updated. New sections for continuous glucose monitoring, insulin pump use, and non-alcoholic fatty liver disease in patients with diabetes mellitus have been added. The KDA recommends active vaccination for coronavirus disease 2019 in patients with diabetes during the pandemic. An abridgement that contains practical information for patient education and systematic management in the clinic was published separately.

A simple soft lithographic nanopatterning of gold on gallium arsenide via galvanic displacement.

Nanoscale patterning of gold layers on GaAs substrate is demonstrated using a combination of soft lithographic molding and galvanic displacement deposition. First, an electroless deposition method has been developed to plate gold on GaAs with ease and cost-effectiveness. The electroless metallization process is performed by dipping the GaAs substrates into a gold salt solution without any reducing agents or additives. The deposition proceeds via galvanic displacement in which gold ions in the aqueous solution are reduced by electrons arising from the GaAs substrate itself. The deposition rate, surface morphology and adhesion property can be modulated by the plating parameters such as the choice of acids and the immersion time. Second, soft lithographic patterning of nanodots, nanorings, and nanolines are demonstrated on GaAs substrates with hard-polydimethylsiloxane (h-PDMS) mold and plasma etching. This method can be easily applied to the metallization and nanopatterning of gold on GaAs surfaces.

Data Configuration and Publication Trends for the Korean National Health Insurance and Health Insurance Review & Assessment Database.

Background: Big data reports related to diseases and health care for the Korean population have been published since the National Health Insurance Service (NHIS) and the Health Insurance Review & Assessment (HIRA) Service provided limited open access to their databases. Here, we reviewed the structure, content, and means of using data from the National Health Insurance (NHI) system for the benefit of Korean researchers and presented the latest publication trends in Korean healthcare data procured from the NHI and HIRA databases. METHODS: Since 2013, researchers have been able to obtain nationwide population-based studies using the NHI and HIRA databases of the insured. We searched publications using the NHI and the HIRA databases between 2013 and 2019 retrieved from PubMed. RESULTS: The NHI and HIRA databases provide nationwide population-based data. The total number of publications from 2014 to 2019 using NHI and HIRA databases is 2,541 and 655, respectively. A total of 5,465 endocrinology-related studies were performed during 2014 to 2019. CONCLUSION: The NHIS and HIRA databases have provided tools for guidelines to approach world-leading population-based epidemiology and disease research.