Association of vitamin B12 deficiency and metformin use in patients with type 2 diabetes

We evaluated the prevalence of vitamin B12 deficiency and associated factors in type 2 diabetes patients using metformin. A total of 799 type 2 diabetes patients using metformin was enrolled. Vitamin B12 and folate levels were quantified by chemiluminescent enzyme immunoassay. Vitamin B12 deficiency was defined as vitamin B12 ≤ 300 pg/mL without folate deficiency (folate > 4 ng/mL). The prevalence of vitamin B12 deficiency in metformin-treated type 2 diabetes patients was 9.5% (n = 76), and the mean vitamin B12 level was 662.5 ± 246.7 pg/mL. Vitamin B12 deficient patients had longer duration of metformin use (P < 0.001) and higher daily metformin dose (P < 0.001) than non-deficient patients. Compared with daily metformin dose of ≤ 1,000 mg, the adjusted odds ratio for 1,000-2,000 mg, and ≥ 2,000 mg were 2.52 (95% CI, 1.27-4.99, P = 0.008) and 3.80 (95% CI, 1.82-7.92, P < 0.001). Compared with metformin use of < 4 yr, the adjusted odds ratios for 4-10 yr, and ≥ 10 yr were 4.65 (95% CI, 2.36-9.16, P < 0.001) and 9.21 (95% CI, 3.38-25.11, P < 0.001), respectively. In conclusion, our study indicates that patients with type 2 diabetes treated with metformin should be screened for vitamin B12 deficiency, especially at higher dosages (> 1,000 mg) and longer durations (≥ 4 yr) of treatment.

Glycaemic and haemoglobin A1c thresholds for detecting diabetic retinopathy: the fifth Korea National Health and Nutrition Examination Survey (2011)

AIMS

Few representative population-based data are available regarding glycaemic and HbA1c thresholds for detecting diabetic retinopathy (DR) in Asia. We investigated the association between DR and fasting plasma glucose (FPG) and HbA1c levels among Korean adults.

METHODS

Using data from the Korea National Health and Nutrition Examination Survey (2011), a total of 5212 adults (≥19 years old) were analysed. When participants had diabetes mellitus and/or a suspicion of DR in two-field nonmydriatic fundus photography, seven standard photographs were obtained after pupil dilatation (75.9% of men, 75.0% of women among the subjects). DR was defined as the presence of ≥1 retinal microaneurysms or blot haemorrhages with or without more severe lesions. Receiver operating characteristic (ROC) curves were used to determine the optimal cut-off value for HbA1c or FPG.

RESULTS

The overall glycaemic thresholds for DR were 6.3mmol/l for FPG and 6.2% (44mmol/mol) for HbA1c. The optimal thresholds did not differ by age group. The sensitivities and specificities were 82.6% and 91.2% for FPG and 93.9% and 89.7% for HbA1c, respectively. The diagnostic discrimination was better for HbA1c than FPG for DR-area under curve: 0.908 for FPG and 0.953 for HbA1c (p=0.007). After being controlled for other covariates, the odds ratio for the risk of DR increased significantly in a consistent way from 6.2% (44mmol/mol) for HbA1c and 6.3mmol/l for FPG.

CONCLUSIONS

According to these nationally representative data, the current diabetes diagnostic values for FPG and HbA1c based on DR may be lower for the Korean population.

Current status of glycemic control of patients with diabetes in Korea: the fifth Korea national health and nutrition examination survey

BACKGROUND

The Korea National Health and Nutrition Examination Survey (KNHANES) III (2005) reported that 22.9% of individuals with diabetes have a glycated hemoglobin (HbA1c) <6.5% and that 43.5% have an HbA1c <7%. We investigated the levels of glycemic control and the factors associated with glycemic control using data from the KNHANES V (2010 to 2012).

METHODS

Subjects with diabetes diagnosed by a physician or those taking antidiabetic medications were classified as individuals with known diabetes. Of 1,498 subjects aged ≥30 years with diabetes, we excluded 157 individuals who were missing HbA1c data. A total of 1,341 subjects were included in the final analysis.

RESULTS

The prevalence of known diabetes was 7.7% (n=1,498, estimated to be 2.32 million people). The proportions of well-controlled diabetes meeting a HbA1c goal of <6.5% and <7% were 27% and 45.6%, respectively. HbA1c increased as the duration of diabetes increased. HbA1c in subjects with a duration of diabetes ≤5 years was lower than in subjects with a duration >5 years. HbA1c in the group taking only oral hypoglycemic agents (OHAs) was significantly lower than that in the group administered only insulin or OHA and insulin in combination. In logistic regression analysis, a longer duration of diabetes, insulin use and the absence of chronic renal failure were associated with HbA1c levels >6.5%.

CONCLUSION

The level of adequate glycemic control was similar to but slightly improved compared with previous levels. The glycemic control of long-standing diabetes patients is more difficult even though they receive insulin treatment.

Prevalence and determinants of diabetic nephropathy in Korea: Korea national health and nutrition examination survey

BACKGROUND

Diabetic nephropathy is a leading cause of end stage renal disease and is associated with an increased risk of cardiovascular mortality. It manifests as albuminuria or impaired glomerular filtration rate (GFR), and the prevalence of diabetic nephropathy varies with ethnicity. The prevalence of diabetic nephropathy and its determinants in Korean adults have not previously been studied at the national level. This cross-sectional study was undertaken to ascertain the prevalence and determinants of albuminuria and chronic kidney disease (CKD) in Korean patients with diabetes.

METHODS

The Korea National Health and Nutrition Examination Survey (KNHANES) V, conducted in 2011, was used to define albuminuria (n=4,652), and the dataset of KNHANES IV-V (2008-2011) was used to define CKD (n=21,521). Selected samples were weighted to represent the entire civilian population in Korea. Albuminuria was defined as a spot urine albumin/creatinine ratio >30 mg/g. CKD was defined as a GFR <60 mL/min/1.73 m(2).

RESULTS

Among subjects with diabetes, 26.7% had albuminuria, and 8.6% had CKD. Diabetes was associated with an approximate 2.5-fold increased risk of albuminuria, with virtually no difference between new-onset and previously diagnosed diabetes. Only systolic blood pressure was significantly associated with albuminuria, and old age, high serum triglyceride levels, and previous cardiovascular disease (CVD) were related with CKD in subjects with diabetes.

CONCLUSION

Korean subjects with diabetes had a higher prevalence of albuminuria and CKD than those without diabetes. Blood pressure was associated with albuminuria, and age, triglyceride level, and previous CVD were independent determinants of CKD in subjects with diabetes.

Higher prevalence and awareness, but lower control rate of hypertension in patients with diabetes than general population: the fifth korean national health and nutrition examination survey in 2011

BACKGROUND

We investigated the prevalence, awareness, treatment, and control rate of hypertension in Korean adults with diabetes using nationally representative data.

METHODS

Using data of 5,105 adults from the fifth Korea National Health and Nutrition Examination Survey in 2011 (4,389 nondiabetes mellitus [non-DM]), 242 newly diagnosed with DM (new-DM), and 474 previously diagnosed with DM (known-DM), we analyzed the prevalence of hypertension (mean systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or use of antihypertensive medication) and control rate of hypertension (blood pressure [BP] <130/80 mm Hg).

RESULTS

The prevalence of hypertension in diabetic adults was 54.6% (44.4% in new-DM and 62.6% in known-DM, P<0.0001 and P<0.0001, respectively) compared with non-DM adults (26.2%). Compared to non-DM, awareness (85.7%, P<0.001) and treatment (97.0%, P=0.020) rates were higher in known-DM, whereas no differences were found between new-DM and non-DM. Control rate among all hypertensive subjects was lower in new-DM (14.9%), compared to non-DM (35.1%, P<0.001) and known-DM (33.3%, P=0.004). Control rate among treated subjects was also lower in new-DM (25.2%), compared to non-DM (68.4%, P<0.0001) and known-DM (39.9%, P<0.0001).

CONCLUSION

Higher prevalence and low control rate of hypertension in adults with diabetes suggest that stringent efforts are needed to control BP in patients with diabetes, particularly in newly diagnosed diabetic patients.

Statin Discontinuation after Achieving a Target Low Density Lipoprotein Cholesterol Level in Type 2 Diabetic Patients without Cardiovascular Disease: A Randomized Controlled Study

BACKGROUND

This study investigated the rate of relapse of dyslipidemia and the factors which could predict relapse following a short-term statin discontinuation after achieving a target low density lipoprotein cholesterol (LDL-C) level in type 2 diabetic patients without cardiovascular disease (CVD).

METHODS

Ninety-nine subjects on rosuvastatin treatment and whose LDL-C level was lower than 100 mg/dL were randomly assigned to discontinue or maintain statin treatment at a 2:1 ratio. The subjects were followed-up after 10 weeks. A relapse of dyslipidemia was defined as a reascent of LDL-C level to greater than 100 mg/dL.

RESULTS

The statin discontinuation group had a significant rate of relapse compared to the maintenance group (79% vs. 3%, respectively). Pretreatment and baseline lipid levels, their ratios, and hemoglobin A1c level were significantly different between the relapse and nonrelapse groups. The pretreatment and baseline lipid profiles and their ratios were independently associated with relapse. The pretreatment LDL-C level was the most useful parameter for predicting a relapse, with a cutoff of 123 mg/dL. During the follow-up period, no CVD event was noted.

CONCLUSION

The relapse rate of dyslipidemia was high when statins were discontinued in type 2 diabetic patients without CVD. Statin discontinuation should be considered carefully based on the pretreatment lipid profiles of patients.

Prevalence, awareness, and management of obesity in Korea: data from the Korea national health and nutrition examination survey (1998-2011)

BACKGROUND

Obesity is a risk factor for diabetes and several cardiovascular diseases. This study was to investigate the trends in the prevalence, awareness, and management status of obesity among the Korean population for recent 13 years.

METHODS

The prevalence, subjective awareness, and management of obesity were investigated in adults aged ≥19 years by using the data from the Korea National Health and Nutrition Examination Surveys (KNHANES) 1998 to 2011.

RESULTS

The number of participants was 8,117, 5,826, 5,500, 3,025, 6,756, 7,506, 6,255, and 6,155 in the KNHANES in years 1998, 2001, 2005, 2007, 2008, 2009, 2010, and 2011, respectively. The prevalence of obesity was 26.9%, 29.2%, 32.9%, 32.5%, 32.0%, 32.6%, 32.0%, and 32.0% in 1998, 2001, 2005, 2007, 2008, 2009, 2010, and 2011, respectively, while the overall prevalence of obesity and abdominal obesity increased by 1.19-fold and 1.24-fold respectively in 2011 compared against 2001. In general, a gradual increase in the prevalence of severe obesity has been observed as years go by. Furthermore, trends of improvements in obesity awareness and management rates were visible over the period of surveys.

CONCLUSION

Although the management status of obesity has improved during the recent years, more effective strategy to control obesity is needed.

Sarcopenia as a determinant of blood pressure in older Koreans: findings from the Korea National Health and Nutrition Examination Surveys (KNHANES) 2008-2010

BACKGROUND

Blood pressure (BP) is directly and causally associated with body size in the general population. Whether muscle mass is an important factor that determines BP remains unclear.

OBJECTIVE

To investigate whether sarcopenia is associated with hypertension in older Koreans.

PARTICIPANTS

We surveyed 2,099 males and 2,747 females aged 60 years or older.

MEASUREMENTS

Sarcopenia was defined as an appendicular skeletal muscle mass divided by body weight (ASM/Wt) that was <1 SD below the gender-specific mean for young adults. Obesity was defined as a body mass index (BMI) ≥ 25 kg/m(2). Subjects were divided into four groups based on presence or absence of obesity or sarcopenia. Hypertension was defined as a systolic BP (SBP) ≥ 140 mmHg, a diastolic BP (DBP) ≥ 90 mmHg, or a self-reported current use of antihypertensive medications.

RESULTS

The overall prevalence of hypertension in the four groups was as follows 49.7% for non-obese non-sarcopenia, 60.9% for non-obese sarcopenia, 66.2% for obese non-sarcopenia and 74.7% for obese sarcopenia. After adjustment for age, gender, regular activity, current smoking and alcohol use, the odds ratio (OR) for having hypertension was 1.5 (95% confidence interval (CI) = 1.23-1.84) in subjects in the non-obese sarcopenia group, 2.08 (95% CI = 1.68-2.57) in the obese non-sarcopenia group and 3.0 (95% CI = 2.48-3.63) in the obese sarcopenia group, compared with the non-obese non-sarcopenia group (p for trend <0.001). Controlling further for body weight and waist circumference did not change the association between hypertension and sarcopenia. The association between sarcopenia and hypertension was more robust in the subjects with diabetes mellitus.

CONCLUSION

Body composition beyond BMI has a considerable impact on hypertension in elderly Koreans. Subjects with sarcopenic obesity appear to have a greater risk of hypertension than simply obese or sarcopenia subjects.

Cardiovascular autonomic dysfunction predicts severe hypoglycemia in patients with type 2 diabetes: a 10-year follow-up study

OBJECTIVE The aim of this study was to investigate the development of severe hypoglycemia (SH) in the presence of cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS From January 2001 to December 2002, a total of 894 patients with type 2 diabetes were enrolled. A cardiovascular autonomic function test (AFT) was performed using the following heart rate variability parameters: expiration-to-inspiration ratio, response to Valsalva maneuver, and standing. From the results for each of the three tests (0 for normal, 1 for abnormal), a total AFT score of 1 was defined as early CAN, and an AFT score of ≥2 was defined as definite CAN. RESULTS The median follow-up time was 9.5 years. The mean age was 54.5 ± 10.1 years, and the mean duration of diabetes was 8.9 ± 6.3 years. One hundred ninety-six patients (31.4%) showed an abnormal cardiovascular AFT score at baseline. Sixty-two patients (9.9%) experienced 77 episodes of SH (1.33 per 100 patient-years). The number of SH events increased as the CAN score increased (23 patients [5.4%] with normal score; 17 patients [17.2%] with early CAN; and 22 patients [22.7%] with definite CAN; P for trends < 0.001). Cox proportional hazards regression analysis revealed that SH was associated with definite CAN (normal vs. definite CAN: hazard ratio 2.43 [95% CI 1.21-4.84]; P = 0.012). CONCLUSIONS Definite CAN was an independent prognostic factor for the development of SH in patients with type 2 diabetes.

Reprogramming of enteroendocrine K cells to pancreatic β-cells through the combined expression of Nkx6.1 and Neurogenin3, and reaggregation in suspension culture

Recent studies have demonstrated that adult cells such as pancreatic exocrine cells can be converted to pancreatic β-cells in a process called cell reprogramming. Enteroendocrine cells and β-cells share similar pathways of differentiation during embryonic development. Notably, enteroendocrine K cells express many of the key proteins found in β-cells. Thus, K cells could be reprogrammed to β-cells under certain conditions. However, there is no clear evidence on whether these cells convert to β-cells. K cells were selected from STC-1 cells, an enteroendocrine cell line expressing multiple hormones. K cells were found to express many genes of transcription factors crucial for islet development and differentiation except for Nkx6.1 and Neurogenin3. A K cell clone stably expressing Nkx6.1 (Nkx6.1(+)-K cells) was established. Induction of Neurogenin3 expression in Nkx6.1(+)-K cells, by either treatment with a γ-secretase inhibitor or infection with a recombinant adenovirus expressing Neurogenin3, led to a significant increase in Insulin1 mRNA expression. After infection with the adenovirus expressing Neurogenin3 and reaggregation in suspension culture, about 50% of Nkx6.1(+)-K cells expressed insulin as determined by immunostaining. The intracellular insulin content was increased markedly. Electron microscopy revealed the presence of insulin granules. However, glucose-stimulated insulin secretion was defective, and there was no glucose lowering effect after transplantation of these cells in diabetic mice. In conclusion, we demonstrated that K cells could be reprogrammed partially to β-cells through the combined expression of Nkx6.1 and Neurogenin3, and reaggregation in suspension culture.

Prevalence and Management of Dyslipidemia in Korea: Korea National Health and Nutrition Examination Survey during 1998 to 2010

BACKGROUND

Dyslipidemia is a major risk factor of cardiovascular disease. The aim of this study was to investigate the changing trends in the prevalence and management status of dyslipidemia among Korean adults.

METHODS

The prevalence of dyslipidemia and the rates of awareness, treatment, and control of dyslipidemia were investigated in adults aged ≥20 years from the Korea National Health and Nutrition Surveys (KNHANES) 1998 to 2010. The updated National Cholesterol Education Program criteria was used, which define dyslipidemia as having one or more of the following lipid abnormalities: hypercholesterolemia (total cholesterol ≥240 mg/dL or diagnosis of dyslipidemia or use of lipid-lowering drugs), hypertriglyceridemia (≥150 mg/dL), hyper-low density lipoprotein (LDL) cholesterolemia (≥160 mg/dL or diagnosis of dyslipidemia or use of lipid-lowering drugs), and hypo-high density lipoprotein (HDL)-cholesterolemia (<40 mg/dL in men and <50 mg/dL in women).

RESULTS

The number of participants was 6,921, 4,894, 5,312, 2,733, 6,295, 6,900, and 5,738 in KNHANES 1998, 2001, 2005, 2007, 2008, 2009, and 2010, respectively. Age-standardized prevalence rates of dyslipidemia were 54.0%, 65.8%, 66.5%, 60.6%, 58.7%, 58.9%, and 59.0% in 1998, 2001, 2005, 2007, 2008, 2009, and 2010, respectively. Hypertriglyceridemia and hypo-HDL-cholesterolemia were the two most frequent lipid abnormalities. The overall prevalence of hypercholesterolemia and hyper-LDL-cholesterolemia increased by 1.36- and 1.35-fold in 2010 compared with 2007, respectively. Awareness, treatment, and control rates of dyslipidemia improved over the period of surveys in both sexes. In 2010, about 30% of dyslipidemic patients who received lipid-lowering treatment reached target levels.

CONCLUSION

Although the management status of dyslipidemia has improved during recent years, effective strategy is required for achieving better prevention, treatment, and control of dyslipidemia.

Prevalence of Diabetes and Prediabetes according to Fasting Plasma Glucose and HbA1c

BACKGROUND

Due to the inconvenience of performing oral glucose tolerance tests and day to day variability in glucose level, glycated hemoglobin (HbA1c) has been recommended by the American Diabetes Association as a method to diagnose diabetes. In addition, the Korean Diabetes Association has also recommended the use of HbA1c as a diagnostic test for diabetes. In this study, we evaluated the prevalence of diabetes according to fasting plasma glucose (FPG) level only or the combination of FPG and HbA1c tests.

METHODS

Data from the 2011 Korea National Health and Nutrition Examination Survey (KNHANES) were analyzed. Among 5,811 subjects aged 30 years or older, 5,020 were selected after excluding the data of fasting time <8 hours, missing values from fasting glucose or HbA1c level, previous diagnosis of diabetes made by physicians, or current use of antidiabetic medications. Diabetes was defined as FPG ≥126 mg/dL, previous diagnosis of diabetes made by a medical doctor, current use of antidiabetic medications, and/or HbA1c ≥6.5%. Prediabetes was defined as FPG of 100 to 125 mg/dL and/or HbA1c of 5.7% to 6.4%.

RESULTS

When we used FPG only, the prevalence of diabetes and prediabetes were 10.5% (men, 12.6%; women, 8.5%) and 19.3% (men, 23.8%; women, 14.9%), respectively. When HbA1c was included as a diagnostic test, the prevalence of diabetes and prediabetes increased to 12.4% (men, 14.5%; women, 10.4%) and 38.3% (men, 41%; women, 35.7%), respectively. Participants with HbA1c ≥6.5% and fasting glucose level <126 mg/dL were older and had lower estimated glomerular filtration rate.

CONCLUSION

We concluded that using fasting glucose level only may result in an underestimation of diabetes and prediabetes. HbA1c is an acceptable complementary diagnostic test for diabetes in Korean patients. However, national standardization is needed to order to use HbA1c as a diagnostic method of diabetes and prediabetes.

Exendin-4 inhibits iNOS expression at the protein level in LPS-stimulated Raw264.7 macrophage by the activation of cAMP/PKA pathway

Glucagon-like peptide-1 (GLP-1) and its potent agonists have been widely studied in pancreatic islet β-cells. However, GLP-1 receptors are present in many extrapancreatic tissues including macrophages, and thus GLP-1 may have diverse actions in these tissues and cells. Therefore, we examined the mechanism by which exendin-4 (EX-4), a potent GLP-1 receptor agonist, inhibits lipopolysaccharide (LPS)-induced iNOS expression in Raw264.7 macrophage cells. EX-4 significantly inhibited LPS-induced iNOS protein expression and nitrite production. However, Northern blot and promoter analyses demonstrated that EX-4 did not inhibit LPS-induced iNOS mRNA expression and iNOS promoter activity. Electrophoretic mobility shift assay (EMSA) showed that EX-4 did not alter the binding activity of NF-κB to the iNOS promoter. Consistent with the result of EMSA, LPS-induced IκBα phosphorylation and nuclear translocation of p65 were not inhibited by EX-4. Also, actinomycin D chase study and the promoter assay using the construct containing 3'-untranslated region of iNOS showed that EX-4 did not affect iNOS mRNA stability. Meanwhile, cycloheximide chase study demonstrated that EX-4 significantly accelerated iNOS protein degradation. The EX-4 inhibition of LPS-induced iNOS protein was significantly reversed by adenylate cyclase inhibitors (MDL-12330A and SQ 22536), a PKA inhibitor (H-89) and PKAα gene silencing. These findings suggest that EX-4 inhibited LPS-induced iNOS expression at protein level, but not at transcriptional mechanism of iNOS gene and this inhibitory effect of EX-4 was mainly dependent on cAMP/PKA system.

Diabetic retinopathy and endothelial dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

We investigated the relationship between endothelial dysfunction and diabetic retinopathy (DR) in patients with type 2 diabetes.

METHODS

We used a cross-sectional design to examine 167 patients with type 2 diabetes mellitus. All patients underwent biochemical and ophthalmological examination. We assessed endothelial dysfunction by a flow-mediated vasodilation method of the brachial artery. Changes in vasodilation (flow-mediated vasodilatation, %FMD) were expressed as percent change over baseline values.

RESULTS

The mean±standard deviation of patient age was 54.1±8.6 years. The %FMD was significantly lower in patients with DR than without DR. The prevalence of retinopathy decreased across increasing tertiles of %FMD. After adjusting for patients' age, sex, diabetes duration, use of insulin, use of antihypertensive, antiplatelet, and lipid lowering medications, systolic blood pressure, fasting plasma glucose, 2-hour plasma glucose, glycated hemoglobin, and urinary albumin excretion, participants with a reduced %FMD were more likely to have DR (odds ratio, 11.819; 95% confidence interval, 2.201 to 63.461; P=0.004, comparing the lowest and highest tertiles of %FMD).

CONCLUSION

Endothelial dysfunction was associated with DR, which was most apparent when the endothelial dysfunction was severe. Our study provides insights into the possible mechanism of the influence of endothelial dysfunction on the development of DR.

Presence of macroalbuminuria predicts severe hypoglycemia in patients with type 2 diabetes: a 10-year follow-up study

OBJECTIVE

We investigated the factors that might influence the development of severe hypoglycemia in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

From January 2000 to December 2002, patients with type 2 diabetes aged 25-75 years without chronic kidney disease (estimated glomerular filtration rate ≥60 mL/min/1.73 m(2)) were consecutively recruited (n = 1,217) and followed-up in January 2011 and May 2012. Severe hypoglycemia (SH) was defined as an event requiring the assistance of another person to actively administer glucose, hospitalization, or medical care in an emergency department. We used Cox proportional hazard regression analysis to test the association between SH episodes and potential explanatory variables.

RESULTS

After a median 10.4 years of follow-up, 111 (12.6%) patients experienced 140 episodes of SH, and the incidence was 1.55 per 100 patient-years. Mean age and duration of diabetes were 55.3 ± 9.8 and 9.8 ± 6.5 years, respectively. The incidence of SH events was higher in older patients (P < 0.001), in those with a longer duration of diabetes (P < 0.001), in those who used insulin (P < 0.001) and sulfonylurea (P = 0.003), and in those who had macroalbuminuria (P < 0.001) at baseline. Cox hazard regression analysis revealed that SH was associated with longer duration of diabetes and the presence of macroalbuminuria (normoalbuminuria versus macroalbuminuria: hazard ratio, 2.52; 95% CI 1.31-4.84; P = 0.006).

CONCLUSIONS

The development of SH was independently associated with duration of diabetes and presence of macroalbuminuria, even with normal renal function in patients with type 2 diabetes.

Resveratrol prevents renal lipotoxicity and inhibits mesangial cell glucotoxicity in a manner dependent on the AMPK-SIRT1-PGC1α axis in db/db mice

AIMS/HYPOTHESIS

Many of the effects of resveratrol are consistent with the activation of AMP-activated protein kinase (AMPK), silent information regulator T1 (SIRT1) and peroxisome proliferator-activated receptor (PPAR)γ co-activator 1α (PGC-1α), which play key roles in the regulation of lipid and glucose homeostasis, and in the control of oxidative stress. We investigated whether resveratrol has protective effects on the kidney in type 2 diabetes.

METHODS

Four groups of male C57BLKS/J db/m and db/db mice were used in this study. Resveratrol was administered via gavage to diabetic and non-diabetic mice, starting at 8 weeks of age, for 12 weeks.

RESULTS

The db/db mice treated with resveratrol had decreased albuminuria. Resveratrol ameliorated glomerular matrix expansion and inflammation. Resveratrol also lowered the NEFA and triacylglycerol content of the kidney, and this action was related to increases in the phosphorylation of AMPK and the activation of SIRT1-PGC-1α signalling and of the key downstream effectors, the PPARα-oestrogen-related receptor (ERR)-1α-sterol regulatory element-binding protein 1 (SREBP1). Furthermore, resveratrol decreased the activity of phosphatidylinositol-3 kinase (PI3K)-Akt phosphorylation and class O forkhead box (FOXO)3a phosphorylation, which resulted in a decrease in B cell leukaemia/lymphoma 2 (BCL-2)-associated X protein (BAX) and increases in BCL-2, superoxide dismutase (SOD)1 and SOD2 production. Consequently, resveratrol reversed the increase in renal apoptotic cells and oxidative stress, as reflected by renal 8-hydroxy-deoxyguanosine (8-OH-dG), urinary 8-OH-dG and isoprostane concentrations. Resveratrol prevented high-glucose-induced oxidative stress and apoptosis in cultured mesangial cells through the phosphorylation of AMPK and activation of SIRT1-PGC-1α signalling and the downstream effectors, PPARα-ERR-1α-SREBP1.

CONCLUSIONS/INTERPRETATION

The results suggest that resveratrol prevents diabetic nephropathy in db/db mice by the phosphorylation of AMPK and activation of SIRT1-PGC-1α signalling, which appear to prevent lipotoxicity-related apoptosis and oxidative stress in the kidney.

Chronic resveratrol treatment protects pancreatic islets against oxidative stress in db/db mice

Resveratrol (RSV) has anti-inflammatory and anti-oxidant actions which may contribute to its cardiovascular protective effects. We examined whether RSV has any beneficial effects on pancreatic islets in db/db mice, an animal model of type 2 diabetes. The db/db and db/dm mice (non-diabetic control) were treated with (db-RSV) or without RSV (db-control) (20 mg/kg daily) for 12 weeks. After performing an intraperitoneal glucose tolerance test and insulin tolerance test, mice were sacrificed, the pancreas was weighed, pancreatic β-cell mass was quantified by point count method, and the amount of islet fibrosis was determined. 8-Hydroxydeoxyguanosine (8-OHdG), an oxidative stress marker, was determined in 24 h urine and pancreatic islets. RSV treatment significantly improved glucose tolerance at 2 hrs in db/db mice (P = 0.036), but not in db/dm mice (P = 0.623). This was associated with a significant increase in both pancreas weight (P = 0.011) and β-cell mass (P = 0.016). Islet fibrosis was much less in RSV-treated mice (P = 0.048). RSV treatment also decreased urinary 8-OHdG levels (P = 0.03) and the percentage of islet nuclei that were positive for 8-OHdG immunostaining (P = 0.019). We conclude that RSV treatment improves glucose tolerance, attenuates β-cell loss, and reduces oxidative stress in type 2 diabetes. These findings suggest that RSV may have a therapeutic implication in the prevention and management of diabetes.

High serum ferritin levels are associated with metabolic risk factors in non-obese Korean young adults: Korean National Health and Nutrition Examination Survey (KNHANES) IV

OBJECTIVE

The purpose of this study is to investigate the relationship between serum ferritin levels and metabolic risk factors in nonobese Korean young adults.

DESIGN AND SUBJECTS

We analysed the fourth annual Korea National Health and Nutrition Examination Survey (KNHANES) in young adults (aged 19-39 years), conducted between 2007 and 2008. A total of 1542 nonobese [body mass index (BMI) <25 kg/m(2) ] young adults (684 men and 858 women) were enrolled. Using blood pressure and levels of serum triglycerides, plasma glucose and high-density lipoprotein (HDL) cholesterol, the Asian criteria for abdominal obesity (Waist circumference ≥90 cm in men or ≥80 cm in women) was used to identify individuals with metabolic syndrome.

MEASUREMENTS

Data on anthropometry, fasting plasma glucose, insulin, lipid profile and ferritin levels were analysed.

RESULTS

The prevalence of metabolic syndrome was 4·1% for men and 2·7% for women. High fasting glucose and the prevalence of metabolic syndrome increased progressively across three different tertiles of ferritin levels in men. However, high ferritin levels were associated with high triglycerides, low HDL cholesterol and metabolic syndrome in women. After adjustment for age, smoking, alcohol consumption, BMI and ALT levels, low HDL cholesterol (OR 1·66, 95% confidence interval (CI) 1·16-2·36) and the presence of metabolic syndrome (OR 3·87, 95% CI 1·34-11·2) were independently associated with high serum ferritin levels in Korean nonobese young women.

CONCLUSIONS

Our results suggest that elevated serum ferritin levels may be employed as a marker of metabolic syndrome in nonobese young adult women.

Long-term changes of the prevalence and control rate of hypertension among Korean adults with diagnosed diabetes: 1998-2008 Korean National Health and Nutrition Examination Survey

AIMS

We investigated the long-term changes in the prevalence and the control rate of hypertension among Korean adults diagnosed with diabetes.

METHODS

Using data from the Korean National Health and Nutrition Examination Survey (1998-2008), including 1384 adults diagnosed with diabetes, we analyzed changes in the prevalence of hypertension (mean SBP ≥ 140 mmHg, DBP ≥ 90 mmHg, or use of antihypertensive medication) and the control rate of hypertension (BP < 130/80 mmHg).

RESULTS

The prevalence of hypertension in diabetic adults was 50.9% in 1998 and 51.7% in 2008 (P = 0.563). The mean blood pressure decreased from 138.1 ± 1.1/80.0 ± 0.6 mmHg to 124.7 ± 0.8/76.0 ± 0.5 mmHg (P < 0.001); awareness (37.4 to 85.2%, P < 0.001), treatment (37.4 to 81.8%, P < 0.001), and the control rate (20.1 to 34.7%, P = 0.001) steadily increased. The prevalence of hypertension increased significantly more in the obese group compared with the non-obese group (53.3% vs. 49.0% in 1998, P = 0.784; 64.3% vs. 42.0% in 2008, P < 0.0001, respectively, P for trend = 0.0001).

CONCLUSIONS

Although the rates of hypertension treatment have significantly improved, the control rate remains inadequate, and intensive intervention is urgently needed.

Influence of the duration of diabetes on the outcome of a diabetes self-management education program

BACKGROUND

Diabetes education and lifestyle modification are critical components in controlling blood glucose levels of people with type 2 diabetes. Until now, available data on the effectiveness of education with respect to the duration of diabetes are limited. We investigated whether adherence to lifestyle behavior modification prompted by diabetes education was influenced by the duration of diabetes.

METHODS

Two hundred and twenty-five people with type 2 diabetes were recruited for an intensive, collaborative, group-based diabetes education program with annual reinforcement. We divided the patients into two groups based on the duration of their diabetes prior to the education program (≤1 year [≤1Y] vs. ≥3 years [≥3Y]). Dietary habits, physical activity, and the frequency of blood glucose self-monitoring were evaluated with a questionnaire prior to education and at the follow-up endpoint.

RESULTS

The mean follow-up period was 32.2 months. The mean hemoglobin A1c (A1C) value was significantly lower in the ≤1Y group. Self-care behaviors, measured by scores for dietary habits (P=0.004) and physical activity (P<0.001), were higher at the endpoint in the ≤1Y group than in the ≥3Y group. Logistic regression analysis revealed that a longer diabetes duration before education was significantly associated with mean A1C levels greater than or equal to 7.0% (53 mmol/mol).

CONCLUSION

Diabetes duration influenced the effectiveness of diabetes education on lifestyle behavior modification and glycemic control. More-intense, regular, and sustained reinforcement with encouragement may be required for individuals with longstanding type 2 diabetes.