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Abstract: Commonly used tests for the diagnosis of diabetes include measurements of fasting plasma glucose levels and the oral glucose tolerance test (OGTT). Recently, a hemoglobin A1C (A1C) level of 6.5% has been included as a criterion for diabetes diagnosis by the American Diabetes Association. We aimed to determine appropriate A1C cutoff values for identifying patients with diabetes or prediabetes, including impaired glucose tolerance and impaired fasting glucose among Korean adults and to determine whether these cutoffs vary according to age. We recruited 4616 adults without a history of diabetes from 10 university hospitals. A 75-g OGTT and A1C sampling were performed in all examinees. Pointwise area under the receiver operating characteristic curve was used to evaluate the diagnostic accuracy of the A1C cutoff. An A1C threshold of 6.1% proved to be the optimal limit for diagnosing diabetes, with 63.8% sensitivity and 88.1% specificity. The cutoff value increased with age (5.9% in 18–39 years, 6.2% in 40–64 years, and 6.4% in older than 65 years) and were similar for men and women. An A1C cutoff of 5.7% had reasonable sensitivity (48.6%) and specificity (65.7%) for the identification of prediabetes. Further prospective studies should be carried out to determine whether the application of age-specific diagnostic criteria is appropriate. [Copyright &y& Elsevier]

Abstract: Many studies show poor agreement between fasting plasma glucose (FPG)-based and 2-h postchallenge glucose (2-h PG)-based criteria to assess glucose metabolism. We examined the rate of agreement between FPG- and 2-h PG-based criteria in the diagnosis of intermediate hyperglycemia in four representative cohort studies in South Korea and compared the clinical characteristics and biochemical parameters in subjects with impaired fasting glucose (IFG) according to their FPG values. Of 6234 subjects from four population-based studies performed from 1993 to 2000, 4610 individuals with data from a 75g oral glucose tolerance test (OGTT) and no previous history of diabetes were selected. We examined the concordance rate between the FPG and 2-h PG-based criteria. We also investigated the differences in the clinical characteristics and biochemical parameters between individuals with IFG according to their FPG values. The fasting and 2-h PG criteria had large discordance rates in the diagnosis of diabetes and impaired glucose tolerance (IGT) in Korean adults. When individuals with IFG were classified into stage 1 [5.6–6.1mmol/L (100–109mg/dL)] and stage 2 [6.1–7.0mmol/L (110–125mg/dL)] IFG, individuals with stage 2 IFG are more obese and had higher blood pressure and total cholesterol and triglycerides concentrations compared with those with stage 1 IFG. In addition, more individuals with stage 2 IFG were with diabetes as determined by a 2-h PG≥11.1mmol/L (14.1% vs. 1.9%) (P <0.05). Considering the poorer metabolic profile and higher percentage of people with diabetes by OGTT, these data indicate that, in the Korean population, individuals with stage 2 IFG should be treated differently from those with stage 1 IFG. To detect more cases of diabetes, the OGTT is recommended for all individuals with stage 2 IFG and cases with stage 1 IFG with some additional risk factors for diabetes. [Copyright &y& Elsevier]

Abstract: Polycystic ovary syndrome (PCOS) is characterized by insulin resistance and consequent hyperinsulinemia. Insulin resistance also plays an important role in the metabolic syndrome (MS). We conducted a cross-sectional study to determine the prevalence of the MS in young Korean women with PCOS and whether it is associated insulin resistance. One hundred and seventeen young women with PCOS (age: 26±5, 16–39 years) were evaluated for the frequency of MS according to the modified Adult Treatment Panel III. Total testosterone (T), free T, androstenedione, dehydroepiandrosterone sulfate (DHEAS) and sex hormone binding globulin (SHBG) were measured, and insulin sensitivity was evaluated by euglycemic hyperinsulinemic clamp technique. The prevalence of MS in women with PCOS was 14.5%, nearly 3.5-fold higher than in age-matched women in Korean urban population (4.3%) [J.-Y. Oh, Y.-A. Sung, Y.S. Hong, E. Barrett-Conner, Prevalence and factor analysis of metabolic syndrome in an urban Korean population, Diabetes Care 27 (2004) 2027–2032]. The most frequently occurring component of MS was low HDL cholesterol (45%), and the least frequent was high fasting serum glucose level (0.9%). PCOS women with MS had significantly higher free T, and lower SHBG compared with those without MS. And women with MS showed significantly lower M-value and higher fasting/post-glucose load insulin levels. M-value was still significantly lower in women with MS even after the adjustment for BMI. MS is frequent in young Korean women with PCOS and it reflects more severe insulin resistance. These results suggest the importance of early and regular screening of metabolic disturbance in even young women with PCOS. [Copyright &y& Elsevier]

Abstract: Over 50% of women with polycystic ovary syndrome (PCOS) have been reported to have varying degree of insulin resistance and it may contribute to hyperandrogenism. The aim of the study is to identify whether the insulin resistance is present in non-obese Korean women with PCOS and whether the phenotype is different according to insulin sensitivity. Seventy-three non-obese (BMI<23kg/m2) women with PCOS and 34 age and BMI comparable control women with regular menstrual cycles were examined. Standard 75g OGTT was performed to determine the status of glucose tolerance. Insulin sensitivity was measured by euglycemic hyperinsulinemic clamp technique. The fasting plasma glucose (p <0.01) and post-glucose load plasma insulin (p <0.01) of women with PCOS were higher than those of controls. Glucose disposal rate (M-value) was lower in women with PCOS compared to controls (p <0.05). Insulin resistant (IR) and insulin sensitive (IS) PCOS were divided by the M-value of 25-percentile (5.5mg/kgmin) in controls. Between IR and IS groups, DHEAS (p <0.01), post-glucose load plasma insulin (p <0.05) showed differences after the adjustment for BMI. Our non-obese women with PCOS showed significant insulin resistance compared to their age and BMI comparable control subjects and their insulin resistance may contribute to hyperandrogenism especially via adrenal androgen overproduction. [Copyright &y& Elsevier]