Oxidative stress has been paid increasing attention to as an important causative factor for diabetic vascular complications. Among possible various sources, accumulating evidence has indicated that NAD(P)H oxidase may be the most important source for reactive oxygen species production in diabetic vascular tissues. The mechanisms underlying activation and up-regulation of NAD(P)H oxidase has been supposed to be mediated by high glucose-induced protein kinase C (PKC) activation. In this review article, activation of local renin-angiotensin II system induced by chymase activation is also shown to amplify such a PKC-dependent activation of NAD(P)H oxidase. Additionally, human evidence showing the beneficial effect of antioxidants on diabetic vascular complications. Bilirubin has been recognized as a strong endogenous antioxidant. Here markedly lower prevalence of vascular complications is shown in diabetic patients with Gilbert syndrome, a congenital hyperbilirubinemia, as well as reduced markers of oxidative stress and inflammation. Lastly, statin, angiotensin II receptor blocker, chymase inhibitor, bilirubin and biliverdin, PKC β isoform inhibitor, and glucagon-like peptide-1 analog, are shown to serve as antioxidants and have some beneficial effect on diabetic vascular complications, via inhibiting PKC-NAD(P)H oxidase activation, supporting the notion that this mechanism may be an effective therapeutic target for preventing diabetic vascular complications.
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Non-alcoholic fatty liver disease (NAFLD), one of the most common liver diseases, is caused by the disruption of hepatic lipid homeostasis. It is associated with insulin resistance as seen in type 2 diabetes mellitus. Glucagon-like peptide-1 (GLP-1) is an incretin that increases insulin sensitivity and aids glucose metabolism. In recent
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Obstructive sleep apnea (OSA) is a chronic disorder that is prevalent, especially in subjects with obesity or diabetes. OSA is related to several metabolic abnormalities, including diabetes, insulin resistance, hypertension, and cardiovascular diseases. Although Koreans are less obese than Caucasians, the prevalence of OSA is comparable in both groups. Thus, the impact of OSA on metabolism may be similar. Many epidemiologic and experimental studies have demonstrated that OSA is associated with glucose intolerance and insulin resistance via intermittent hypoxia, sleep fragmentation, and sleep deprivation. The effect of continuous positive airway pressure treatment on glucose metabolism is still controversial. Randomized controlled trials are needed to evaluate the ability of OSA treatment to reduce the risk of diabetes and insulin resistance in subjects without diabetes and to ameliorate glucose control in patients with diabetes.
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The aim of this study was to investigate the effects of balsamic vinegar on β-cell dysfunction.
In this study, 28-week-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats were fed a normal chow diet or a high-fat diet (HFD) and were provided with tap water or dilute balsamic vinegar for 4 weeks. Oral glucose tolerance tests and histopathological analyses were performed thereafter.
In rats fed both the both chow diet and the HFD, the rats given balsamic vinegar showed increased insulin staining in islets compared with tap water administered rats. Balsamic vinegar administration also increased β-cell ATP-binding cassette transporter subfamily A member 1 (ABCA1) expression in islets and decreased cholesterol levels.
These findings provide the first evidence for an anti-diabetic effect of balsamic vinegar through improvement of β-cell function via increasing β-cell ABCA1 expression.
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The prevalence of hypoglycemia is increasing due to the growing incidence of diabetes and the latest strict guidelines for glycated hemoglobin (HbA1c) levels under 7%. This study examined the clinical characteristics, causal factors, and medical costs of severely hypoglycemic patients in an emergency room (ER) of Uijeongbu St. Mary's Hospital.
The study consisted of a retrospective analysis of the characteristics, risk factors, and medical costs of 320 severely hypoglycemic patients with diabetes who presented to an ER of Uijeongbu St. Mary's Hospital from January 1, 2006 to December 31, 2009.
Most hypoglycemic patients (87.5%, 280/320) were over 60 years old with a mean age of 69.5±10.9 years and a mean HbA1c level of 6.95±1.46%. Mean serum glucose as noted in the ER was 37.9±34.5 mg/dL. Renal function was decreased, serum creatinine was 2.0±2.1 mg/dL and estimated glomerular filtration rate (eGFR) was 48.0±33.6 mL/min/1.73 m2. In addition, hypoglycemic patients typically were taking sulfonylureas or insulin and a variety of other medications, and had a long history of diabetes.
Severe hypoglycemia is frequent in older diabetic patients, subjects with low HbA1c levels, and nephropathic patients. Therefore, personalized attention is warranted, especially in long-term diabetics with multiple comorbidities who may not have been properly educated or may need re-education for hypoglycemia.
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The aim of this study was to investigate the influences of visceral adiposity on cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus.
Two hundred eleven patients with type 2 diabetes participated in this study. Anthropometric and metabolic parameters were measured, and the visceral fat area was assessed using computed tomography. CAN was diagnosed using a cardiovascular reflex test. We analyzed the correlation between the visceral fat area and each parameter in this test.
The mean age, body mass index (BMI), and duration of diabetes of the study population were 60±14 years (mean±standard deviation), 25.1±4.2 kg/m2, and 12.3±8.9 years, respectively. The visceral fat area showed positive correlations with age, BMI, waist circumference, and subcutaneous fat area. There was no statistically significant difference in the cardiovascular reflex test outcome between genders. Univariate linear regression analysis showed that an increased visceral fat area diminished good heart rate response to a Valsalva maneuver (
The results of this study suggest that visceral adiposity contributes to an autonomic imbalance to some degree, as demonstrated by the impaired cardiovascular reflex test among women with type 2 diabetes.
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Metformin, an oral biguanide insulin-sensitizing agent, is well known to decrease appetite. Although there is evidence that metformin could affect the brain directly, the exact mechanism is not yet known.
To evaluate whether metformin induces anorexia via the hypothalamus, various concentrations of metformin were injected into the lateral ventricle of rats through a chronically implanted catheter and food intake was measured for 24 hours. The hypothalamic neuropeptides associated with regulation of food intake were also analyzed following 1 hour of intracerebroventricular (ICV) injections of metformin.
An ICV injection of metformin decreased food intake in a dose-dependent manner in unrestrained conscious rats. Hypothalamic phosphorylated AMP-activated protein kinase (pAMPK) increased by 3 µg with metformin treatment, but there was no further increase in pAMPK with increases in metformin dosage. The hypothalamic phosphorylated signal transducer and activator of transcription 3 (pSTAT3) increased by 3 µg with metformin treatment, but, there was no further increase in pSTAT3 level following increases of metformin dosage. Hypothalamic proopiomelanocortin was elevated with metformin treatment, while neuropeptide Y was not significantly changed.
Our results suggest that metformin induces anorexia via direct action in the hypothalamus and the increase in pSTAT3, at least in part, is involved in the process. However, hypothalamic pAMPK appears not to contribute to metformin-induced appetite reduction in normal rats. Further studies exploring new pathways connecting metformin and feeding regulation are needed.
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Major macronutrients for energy intake vary among countries and cultures. Carbohydrates, including rice, are the major component of daily energy intake in Korea. The aim of this study was to examine the association of daily energy intake or each proportion of macronutrients, especially carbohydrates, with glycemic control in diabetic Koreans.
A total of 334 individuals with diabetes (175 men, age 57.4±0.8 years; 159 women, age 60.9±0.9 years) who participated in the 2005 Korean National Health and Nutrition Examination Survey were examined. Glycemic control was categorized based on concentration of glycated hemoglobin (HbA1c; HbA1c ≤6.5%; 6.6% to 8.0%; ≥8.1%). Dietary intake was assessed by using a 24-recall item questionnaire.
High total energy intake was associated with poor glycemic control (HbA1c ≤6.5%, 1,824±75 kcal; 6.6% to 8.0%, 1,990±57 kcal; ≥8.1%, 2,144±73 kcal;
Total energy intake may be more closely related to glycemic control than each proportionof macronutrients in Korean diabetics.
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Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker of acute kidney injury. There is a growing body of evidence suggesting that NGAL is also a marker of kidney disease and severity in chronic kidney disease (CKD). We studied the utility of urinary NGAL in more accurately predicting renal function in patients with diabetic CKD.
We studied possible relationships between urinary NGAL, estimated glomerular filtration rate (eGFR), and proteinuria in diabetic CKD patients and in healthy populations.
Urinary NGAL levels were significantly higher in CKD patients than in healthy controls (96.0 [2.7 to 975.2] ng/mL vs. 18.8 [1.3 to 81.9] ng/mL,
From these results, we concluded that urinary NGAL is a reliable marker of renal function in diabetic CKD patients. However, urinary NGAL did not provide more accurate information regarding renal function than GFR.
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