Insulin Resistance, Non-Alcoholic Fatty Liver Disease and Type 2 Diabetes Mellitus: Clinical and Experimental Perspective.

It has been generally accepted that insulin resistance (IR) and reduced insulin secretory capacity are the basic pathogenesis of type 2 diabetes mellitus (T2DM). In addition to genetic factors, the persistence of systemic inflammation caused by obesity and the associated threat of lipotoxicity increase the risk of T2DM. In particular, the main cause of IR is obesity and subjects with T2DM have a higher body mass index (BMI) than normal subjects according to recent studies. The prevalence of T2DM with IR has increased with increasing BMI during the past three decades. According to recent studies, homeostatic model assessment of IR was increased compared to that of the 1990s. Rising prevalence of obesity in Korea have contributed to the development of IR, non-alcoholic fatty liver disease and T2DM and cutting this vicious cycle is important. My colleagues and I have investigated this pathogenic mechanism on this theme through clinical and experimental studies over 20 years and herein, I would like to summarize some of our studies with deep gratitude for receiving the prestigious 2023 Sulwon Award.

Coronary Artery Calcium Score as a Sensitive Indicator of Cardiovascular Disease in Patients with Type 2 Diabetes Mellitus: A Long-Term Cohort Study.

BACKGRUOUND: Coronary artery calcium score (CACS) has become an important tool for evaluating cardiovascular disease (CVD). This study evaluated the significance of CACS for future CVD through more than 10 years of follow-up in asymptomatic Korean populations with type 2 diabetes mellitus (T2DM) known to have a relatively low CACS burden. METHODS: We enrolled 981 asymptomatic T2DM patients without CVD at baseline who underwent CACS evaluation using multidetector computed tomography between January 2008 and December 2014. They were grouped into five predefined CACS categories based on Agatston scores and followed up by August 2020. The primary endpoint was incident CVD events, including coronary, cerebrovascular, and peripheral arterial disease. RESULTS: The relative risk of CVD was significantly higher in patients with CACS ≥10, and the significance persisted after adjustment for known confounders. A higher CACS category indicated a higher incidence of future CVD: hazard ratio (95% confidence interval) 4.09 (1.79 to 9.36), 12.00 (5.61 to 25.69), and 38.79 (16.43 to 91.59) for 10≤ CACS <100, 100≤ CACS <400, and CACS ≥400, respectively. During the 12-year follow-up period, the difference in event-free survival more than doubled as the category increased. Patients with CACS below 10 had very low CVD incidence throughout the follow-up. The receiver operating characteristic analysis showed better area under curve when the CACS cutoff was 10 than 100. CONCLUSION: CACS can be a sensitive marker of CVD risk. Specifically, CACS above 10 is an indicator of CVD high-risk requiring more intensive medical treatment in Koreans with T2DM.

Increased Risk of NAFLD in Adults with Glomerular Hyperfiltration: An 8-Year Cohort Study Based on 147,162 Koreans.

This study evaluated whether glomerular hyperfiltration (GHF) could predict nonalcoholic fatty liver disease (NAFLD) and fibrosis. A longitudinal cohort study including 147,479 participants aged 20-65 years without NAFLD and kidney disease at baseline was performed. GHF cutoff values were defined as age- and sex-specific estimated glomerular filtration rate (eGFRs) above the 95th percentile, and eGFR values between the 50th and 65th percentiles were used as reference groups. NAFLD was diagnosed via abdominal ultrasonography, and the fibrosis status was evaluated using the NAFLD fibrosis score and Fibrosis-4. During 598,745 person years of follow-up (median, 4.6 years), subjects with GHF at baseline had the highest hazard ratio (HR) for the development of NAFLD (HR 1.21; 95% CI 1.14-1.29) and fibrosis progression (HR 1.42; 95% CI 1.11-1.82) after adjusting for confounding factors. A higher baseline eGFR percentile maintained a higher risk of NAFLD and fibrosis probability. The persistent GHF group during follow-up had the highest HR for NAFLD compared to the persistent non-GHF group (HR 1.31; 95% CI 1.14-1.51). These results were consistent in all subgroups and statistically more prominent in participants without diabetes. GHF was positively associated with increased risk of NAFLD and probability of liver fibrosis in healthy adults.

Changes in Insulin Resistance Index and the Risk of Liver Fibrosis in Patients with Nonalcoholic Fatty Liver Disease without Diabetes: Kangbuk Samsung Health Study.

BACKGROUND: Fibrosis is the most important prognostic factor for nonalcoholic fatty liver disease (NAFLD). Insulin resistance plays a key role of fibrosis progression. We evaluated the association between changes in homeostasis model assessment of insulin resistance (HOMA-IR) values and changes in fibrosis status in NAFLD. METHODS: We analyzed the data of 15,728 participants with NAFLD (86% men, mean age 40.5 years) who had no diabetes at baseline and visited our centers for health check-ups both in 2012 and 2016. The participants were classified into four groups according to the degree of change in HOMA-IR values from baseline to the end of follow-up: G1 (<0), G2 (0-0.50), G3 (0.51-1.00), and G4 (>1.00). NAFLD was assessed by ultrasonography, and fibrosis status was evaluated by the NAFLD fibrosis score (NFS) and the aspartate aminotransferase to platelet ratio index (APRI). RESULTS: After the 4-year follow-up, the multivariable-adjusted odds ratio (OR) for progression of fibrosis probability increased with increasing HOMA-IR values (OR, 2.25; 95% confidence interval [CI], 1.87 to 2.71 for NFS; and OR, 2.55; 95% CI, 2.05 to 3.18 for APRI, G4). This tendency remained consistent throughout the subgroup analyses, except in those for female sex and a body mass index <25 kg/m2. The OR for regression of fibrosis probability decreased with increasing HOMA-IR values (OR, 0.33; 95% CI, 0.25 to 0.43 for NFS, G4). CONCLUSION: Changes in HOMA-IR values were associated with changes in fibrosis status in patients with NAFLD without diabetes, which underscores the role of insulin resistance in liver fibrosis.

Increased Risk of Nonalcoholic Fatty Liver Disease in Individuals with High Weight Variability.

BACKGROUND: Weight loss through lifestyle modification is recommended for patients with nonalcoholic fatty liver disease (NAFLD). Recent studies have suggested that repeated loss and gain of weight is associated with worse health outcomes. This study aimed to examine the association between weight variability and the risk of NAFLD in patients without diabetes. METHODS: We examined the health-checkup data of 30,708 participants who had undergone serial examinations between 2010 and 2014. Weight variability was assessed using coefficient of variation and the average successive variability of weight (ASVW), which was defined as the sum of absolute weight changes between successive years over the 5-year period divided by 4. The participants were classified according to the baseline body mass index and weight difference over 4 years. RESULTS: On dividing the participants into four groups according to ASVW quartile groups, those in the highest quartile showed a significantly increased risk of NAFLD compared to those in the lowest quartile (odds ratio [OR], 1.89; 95% confidence interval [CI], 1.63 to 2.19). Among participants without obesity at baseline, individuals with high ASVW showed increased risk of NAFLD (OR, 1.80; 95% CI, 1.61 to 2.01). Participants with increased weight over 4 years and high ASVW demonstrated higher risk of NAFLD compared to those with stable weight and low ASVW (OR, 4.87; 95% CI, 4.29 to 5.53). CONCLUSION: Regardless of participant baseline obesity status, high weight variability was associated with an increased risk of developing NAFLD. Our results suggest that further effort is required to minimize weight fluctuations after achieving a desirable body weight.

Baseline homeostasis model assessment of insulin resistance associated with fibrosis progression in patients with nonalcoholic fatty liver disease without diabetes: A cohort study.

BACKGROUND AND AIMS: Fibrosis progression is the most important prognostic factor, and insulin resistance is one of the main mechanisms associated with fibrosis progression in patients with nonalcoholic fatty liver disease (NAFLD). We evaluate the association between baseline insulin resistance and future fibrosis progression in patients with NAFLD without diabetes. APPROACH AND RESULTS: This retrospective longitudinal study with 8-year follow-up period included 32,606 (men, 83%) participants aged >20 years (average age, 38.0 years) without diabetes at baseline who completed at least two comprehensive health checkups from January 1, 2010 to December 31, 2018. NAFLD was diagnosed based on ultrasonography. The homeostasis model assessment of insulin resistance (HOMA-IR) was used to evaluate baseline insulin resistance. Fibrosis progression was assessed using the aspartate aminotransferase to platelet ratio index (APRI). The advanced liver fibrosis with an APRI value above the intermediate fibrosis probability (≥0.5) developed in a total of 2,897 participants during 136,108 person-years. 114 participants progressed to a high fibrosis probability stage (APRI >1.5) during 141,064 person-years. Using the lowest baseline HOMA-IR quartile group (Q1) as a reference, the multivariate-adjusted hazard ratio (HR) for development of advanced liver fibrosis (APRI ≥0.5) in the highest baseline HOMA-IR quartile group (Q4) was 1.95 (95% confidence interval [CI] 1.74-2.19; Model 4). And the HR for development of advanced liver fibrosis with high fibrosis probability was 1.95 (95% CI 1.10-3.46; Model 4). The positive association was maintained throughout the entire follow-up period. The baseline HOMA-IR model was superior to the baseline body mass index (BMI) model in predicting the progression of fibrosis probability. CONCLUSIONS: In this longitudinal study, we found that the degree of baseline insulin resistance, assessed by HOMA-IR values, was positively associated with future fibrosis progression in patients with NAFLD without diabetes.

Dexamethasone or Dexmedetomidine as Local Anesthetic Adjuvants for Ultrasound-guided Axillary Brachial Plexus Blocks with Nerve Stimulation.

BACKGROUND: The purpose of this study was to evaluate the effect of dexamethasone or dexmedetomidine added to ropivacaine on the onset and duration of ultrasound-guided axillary brachial plexus blocks (BPB). METHODS: Fifty-one ASA physical status I-II patients with elective forearm and hand surgery under axillary brachial plexus blocks were randomly allocated to receive 20 ml of 0.5% ropivacaine with 2 ml of isotonic saline (C group, n = 17), 20 ml of 0.5% ropivacaine with 2 ml (10 mg) of dexamethasone (D group, n = 17) or 20 ml of 0.5% ropivacaine with 2 ml (100 µg) of dexmedetomidine (DM group, n = 17). A nerve stimulation technique with ultrasound was used in all patients. The onset time and duration of sensory blocks were assessed. RESULTS: The duration of the sensory block was extended in group D and group DX compared with group C (P < 0.05), but there was no significant difference between group D and group DX. However, there were no significant differences in onset time in all three groups. CONCLUSIONS: Dexamethasone 10 mg and dexmedetomidine 100 µg were equally effective in extending the duration of ropivacaine in ultrasound-guided axillary BPB with nerve stimulation. However, neither drug has significantly effects the onset time.