Sang-Man Jin

Amyloidogenic peptide oligomer accumulation in autophagy-deficient β cells induces diabetes

Islet amyloid accumulation is a hallmark of human type 2 diabetes (T2D). In contrast to human islet amyloid polypeptide (hIAPP), murine islet amyloid polypeptide (mIAPP) does not exhibit amyloidogenic propensity. Because autophagy is important in the clearance of amyloid-like proteins, we studied transgenic mice with β cell-specific expression of hIAPP to evaluate the contribution of autophagy in T2D-associated accumulation of hIAPP. In mice with β cell-specific expression of hIAPP, a deficiency in autophagy resulted in development of overt diabetes, which was not observed in mice expressing hIAPP alone or lacking autophagy alone. Furthermore, lack of autophagy in hIAPP-expressing animals resulted in hIAPP oligomer and amyloid accumulation in pancreatic islets, leading to increased death and decreased mass of β cells. Expression of hIAPP in purified monkey islet cells or a murine β cell line resulted in pro-hIAPP dimer formation, while dimer formation was absent or reduced dramatically in cells expressing either nonamyloidogenic mIAPP or nonfibrillar mutant hIAPP. In autophagy-deficient cells, accumulation of pro-hIAPP dimers increased markedly, and pro-hIAPP trimers were detected in the detergent-insoluble fraction. Enhancement of autophagy improved the metabolic profile of hIAPP-expressing mice fed a high-fat diet. These results suggest that autophagy promotes clearance of amyloidogenic hIAPP, autophagy deficiency exacerbates pathogenesis of human T2D, and autophagy enhancers have therapeutic potential for islet amyloid accumulation-associated human T2D.

Associations between body mass index and clinico-pathological characteristics of papillary thyroid cancer.

Epidemiological studies have demonstrated that excess weight increases the risk of thyroid cancer. However, the associations between excess weight and prognostic factors for thyroid cancer are uncertain. We evaluated the relationships between body mass index (BMI) and clinico‐pathological features and outcomes of papillary thyroid cancer (PTC).

Co‐Transplantation of Bone Marrow‐Derived Endothelial Progenitor Cells Improves Revascularization and Organization in Islet Grafts

Bone marrow‐derived early endothelial progenitor cells (BM‐EPCs) are a clinical tool for enhancing revascularization. However, the therapeutic efficacy of co‐transplantation of BM‐EPC with islets has not been investigated. In this study, marginal mass islets were co‐transplanted with or without BM‐EPCs under the kidney capsules of syngeneic streptozotocin‐induced diabetic mice. Using green fluorescent protein transgenic (GFP‐Tg) mice as BM‐EPC and islet donors or recipients, the role of EPCs in revascularization was assessed for graft morphology, vascular density and fate of EPCs by immunohistochemistry. Islet‐EPC co‐transplantation improved the outcome of islet transplantation as measured by glucose tolerance, serum insulin level and diabetes reversal rate, compared with transplantation of islets alone. Between groups, the morphology of islet grafts showed significant differences in size and composition of grafted endocrine tissues. Significantly more vessel density derived from donors and recipients was detected with islet‐EPC co‐transplantation. Abundant GFP‐Tg mice‐derived BM‐EPCs (GFP‐EPCs) were observed in or around islet grafts and incorporated into CD31‐positive capillaries. Remaining GFP‐EPCs expressed VEGF. In conclusion, co‐transplantation of islets with BM‐EPCs could improve the outcome of marginal mass islet transplantation by promoting revascularization and preserving islet morphology.

Non-HDL-cholesterol/HDL-cholesterol is a better predictor of metabolic syndrome and insulin resistance than apolipoprotein B/apolipoprotein A1

BACKGROUND The ratio of apolipoprotein B (apoB) to apolipoprotein A1 (apoA1) has been reported to be associated with metabolic syndrome (MetS) and insulin resistance (IR). Non-HDL-C is regarded as a surrogate marker for apoB in routine clinical practice. However, it is unclear whether the ratio of non-HDL-C to HDL-C is an equal or a better predictor than the apoB/apoA1 ratio for the identification of MetS and IR. METHODS We performed a retrospective study of 41,821 Korean adults who participated in a routine health screening examination. Anthropometry, fasting glucose, fasting insulin, HOMA-IR, CRP, lipid profiles, apoB, and apoA1 were measured. RESULTS To compare the predictive value for MetS between different lipid ratios, we analyzed the ROC curves of apoB/apoA1 and non-HDL-C/HDL-C ratios. ROC analysis showed that the AUCs of non-HDL-C/HDL-C (0.75 [95% CI=0.74-0.76] in men and 0.84 [95% CI=0.83-0.85] in women) were significantly higher than those of apoB/apoA1 (0.66 [95% CI=0.65-0.67] in men and 0.77 [95% CI=0.76-0.78] in women). The non-HDL-C/HDL-C ratio also showed a significantly stronger association with HOMA-IR than the apoB/apoA1 ratio. The optimal cutoff value of the non-HDL-C/HDL-C ratio for detection of MetS in men was 3.39, with a sensitivity of 66.7% and a specificity of 71.8%, whereas the optimal ratio cutoff value in women was 2.89, with a sensitivity of 75.7% and a specificity of 78.1%. CONCLUSIONS Our findings indicate that the non-HDL-C/HDL-C ratio is a better marker than the apoB/apoA1 ratio for identifying IR and MetS in Koreans.

Serum uric acid: A strong and independent predictor of metabolic syndrome after adjusting for body composition

BACKGROUND Some observational studies have suggested that serum uric acid (SUA) levels are one of the determinants of the metabolic syndrome (MetS). However, previous studies reported combined results for men and women after adjusting for sex and few studies take body composition into consideration. Therefore, we performed this sex-specific longitudinal study to investigate how baseline SUA levels influence incident MetS, including body composition as an adjusting factor in a large number of subjects. METHODS A total of 14,442 participants (8715 men and 5727 women) participating in a medical health check-up program without diagnosed MetS at baseline were enrolled. Separate analyses were performed for men and women including body composition as a confounding factor. Cox proportional hazards models were used to quantify independent associations between SUA levels and incident MetS. RESULTS During 63,940person-years of follow-up, there were 4215 (2974 men, 1241 women) incident cases of MetS between 2006 and 2012. After adjustments for age, systolic BP, diastolic BP, BMI, eGFR, smoking status, TG, LDL-C, HDL-C, fasting glucose, and proportion of fat-free mass (100-fat mass, %), the hazard ratios (HR) [95% confidence interval (CI)] for incident MetS comparing the second, the third, and the fourth quartiles to the first quartile of SUA levels were 0.862 (0.770-0.965), 1.102 (0.991-1.225), and 1.246 (1.121-1.385) in men (p for trend<0.001), and 1.045 (0.862-1.266), 1.251 (1.050-1.490), and 1.321 (1.109-1.574) in women (p for trend<0.001), respectively. As a continuous variable, in fully-adjusted models, the HRs (95% CI) for incident MetS associated with each increase of 1mg/dl of SUA levels were 1.094 (1.060-1.130) in men (p<0.001) and 1.148 (1.072-1.228) in women (p<0.001), respectively. CONCLUSION We demonstrated that SUA levels are strong and independent predictors of MetS. This relationship remained significant after full adjustments for multiple associated confounders including body composition in both men and women.

Lobeglitazone and pioglitazone as add‐ons to metformin for patients with type 2 diabetes: a 24‐week, multicentre, randomized, double‐blind, parallel‐group, active‐controlled, phase III clinical trial with a 28‐week extension

We aimed to compare the efficacy and safety of lobeglitazone and pioglitazone as add‐ons to metformin in patients with type 2 diabetes. Patients who were inadequately controlled by metformin were randomized and treated once daily with either lobeglitazone (0.5 mg, n = 128) or pioglitazone (15 mg, n = 125) for 24 weeks, with a 28‐week extension trial of lobeglitazone treatment in patients who consented. The primary endpoint was the change in glycated haemoglobin (HbA1c) concentration from baseline to week 24. At week 24, the mean change from baseline in HbA1c was −0.74% for the lobeglitazone group and −0.74% for the pioglitazone group, with a mean difference of 0.01% [95% confidence interval (CI) of difference, −0.16 to 0.18]. The effects of lobeglitazone on lipid variables and the adverse events associated with lobeglitazone were similar to those observed with pioglitazone. Lobeglitazone was not inferior to pioglitazone as an add‐on to metformin in terms of their efficacy and safety.

Diabetes-free survival in patients who underwent islet autotransplantation after 50% to 60% distal partial pancreatectomy for benign pancreatic tumors.

Background Several retrospective studies with short-term follow-up have demonstrated a low rate of new-onset diabetes after distal pancreatectomy for benign pancreatic tumors. We sought to determine the long-term diabetes-free survival of patients who underwent islet autotransplantation (IAT) after distal pancreatectomy and to identify any associations between the isolation parameters of autologous islets and diabetes-free survival. Methods Among the 37 nondiabetic patients who underwent 50% to 60% partial pancreatectomy, 20 underwent IAT (IAT group; median follow-up period, 61 months). In the IAT group, diabetes-free survival was determined based on annual oral glucose tolerance tests, fasting blood glucose, and hemoglobin A1C. Results The 7-year diabetes-free survival rate was 51% in the IAT group (median follow-up period, 61 months) and 45% in the 37 study subjects. Diabetes-free survival was significantly prolonged when islet yield per gram of pancreas weight was more than 5154 islet equivalents (IEQ)/g, even in patients with prediabetes and high insulin resistance who had a markedly high rate of diabetes development. The proportion of patients with impaired glucose tolerance at 2 years after distal pancreatectomy was 12 of 16 in the control group, 6 of 7 in patients with islet yields of less than 5154 IEQ/g, and 3 of 11 in patients with islet yields of more than 5154 IEQ/g (P=0.019). Conclusions Partial (50%–60%) pancreatectomy for benign pancreatic tumors had a major metabolic consequence, especially in patients with prediabetes and high insulin resistance. In this setting, prolonged diabetes-free survival was observed in patients who underwent IAT when a high islet yield per gram of pancreas was achieved.

Clinical factors associated with absolute and relative measures of glycemic variability determined by continuous glucose monitoring: An analysis of 480 subjects

AIM Factors associated with absolute and relative measures of glycemic variability have not been determined by continuous glucose monitoring (CGM) and concurrent measurement of fasting C-peptide levels. METHODS We analyzed CGM data for subjects with type 1 diabetes (T1D; n=81) and type 2 diabetes (T2D; insulin-treated, n=168; not insulin-treated, n=231) who underwent CGM between October 2009 and September 2011 at Samsung Medical Center. Correlations between clinical factors and both standard deviation (SD) and coefficient of variance (CV) in CGM were analyzed by multiple regression. RESULTS Regardless of the type of diabetes and insulin therapy, higher CV, but not SD, was significantly associated with a minimum glucose level of <70 mg/dL (3.9 mmol/l) in CGM (p<0.001). In T1D, fasting C-peptide levels inversely correlated with SD while BMI inversely correlated with CV, and duration of diabetes, and HDL levels positively correlated with CV. Use of pre-mixed insulin increased both SD and CV. In insulin-treated T2D, fasting C-peptide levels inversely correlated with both SD and CV while HbA1c correlated with SD, and duration of diabetes positively correlated with CV. In T2D without insulin therapy, age, BMI, HbA1c, HDL, triglyceride levels and use of sulfonylurea positively correlated with SD while HDL levels and use of sulfonylurea positively correlated with CV, and LDL levels inversely correlated with CV. CONCLUSIONS Relative glycemic variability (CV) was determined by factors different from those that affect absolute glycemic variability (SD). Some of these factors were indicators of higher insulin sensitivity and residual insulin secretion.

Strong correlation between glycaemic variability and total glucose exposure in type 2 diabetes is limited to subjects with satisfactory glycaemic control

AIMS This study investigated the relationship between markers of overall glucose exposure, postprandial glucose excursions and glycaemic variability in patients with type 2 diabetes mellitus (T2DM). METHODS A total of 63 patients with T2DM (mean age 56 years) were enrolled. All wore a continuous glucose monitoring system (CGMS) device for 72 h to collect data on markers of overall glucose exposure, postprandial glucose excursions and glycaemic variability parameters. RESULTS Spearmans correlation analysis revealed significant correlations between all markers of overall glucose exposure and various parameters related to glucose excursions. The percent coefficient of variation (CV) showed the strongest correlation with glycated albumin (r=0.470, P<0.01). In participants with HbA1c levels < 7.5% (n=33), almost all glycaemic markers and glycaemic variability parameters were significantly correlated with each other. Also, all postprandial glucose excursion parameters showed significant correlation with other glycaemic markers, and all markers of overall glucose exposure were significantly related to mean glucose, postprandial glucose excursions and glycaemic variability parameters (except CV). In contrast, in participants with HbA1c levels ≥ 7.5% (n=30), no parameters of postprandial glucose excursions and glycaemic variability were related to any markers of chronic glycaemia. CONCLUSION Postprandial glucose excursions may explain glycaemic variability and total glucose exposures in well-controlled T2DM patients.

Education as prescription for patients with type 2 diabetes mellitus: compliance and efficacy in clinical practice.

Background Diabetes self-management education has an important role in diabetes management. The efficacy of education has been proven in several randomized trials. However, the status of diabetes education programs in real Korean clinical practice has not yet been evaluated in terms of patient compliance with the education prescription. Methods We retrospectively analyzed clinical and laboratory data from all patients who were ordered to undergo diabetes education during 2009 at Samsung Medical Center, Seoul, Korea (n=2,291). After excluding ineligible subjects, 588 patients were included in the analysis. Results Among the 588 patients, 433 received education. The overall compliance rate was 73.6%, which was significantly higher in the subjects with a short duration or living in a rural area compared to those with a long duration (85.0% vs. 65.1%, respectively; P<0.001) or living in an urban area (78.2% vs. 70.4%, respectively; P=0.037). The hemoglobin A1c decreased greater in the compliant group (from 7.84±1.54 at baseline to 6.79±1.06 at 3 months and 6.97±1.20 at 12 months after prescription in the compliant group vs. from 7.74±1.25 to 7.14±1.02 and 7.24±1.24 in the non-compliant group; P=0.001). The decrease in hemoglobin A1c was greater in the subjects with a short duration (P=0.032). Conclusion In our study a large percent of patients refuse to get education despite having a prescription from their physician. This refusal rate was higher in the patients with long-standing diabetes or in urban residence. Furthermore, education was more effective in patients with a short duration of diabetes in clinical practice.