Background/AimsRecent epidemiological studies revealed a striking inverse relationship between vitamin D levels, glucose intolerance/insulin resistance (IR), and cardiovascular disease. However, few interventional studies have evaluated the effect of vitamin D supplementation on cardiovascular risk, such as IR and arterial stiffness, in diabetes. We investigated the role of vitamin D supplementation on cardiovascular risk in type 2 diabetes patients, including metabolic parameters, IR, and arterial stiffness.MethodsWe enrolled patients who were taking antidiabetic medications or managed their diabetes using lifestyle changes. We excluded patients who were taking vitamin D or calcium supplements. We randomized participants into the vitamin D group (cholecalciferol 2,000 IU/day + calcium 200 mg/day, n = 40) or the placebo group (calcium 200 mg/day, n = 41). We compared their IR (homeostasis model of assessment [HOMA]-IR) and arterial stiffness (brachial-ankle pulse wave velocity and radial augmentation index) before and after 24 weeks of intervention.ResultsThe baseline characteristics of the two groups were similar. A total of 62 participants (placebo, 30; vitamin D, 32) completed the study protocol. At the end of the study period, the 25-hydroxyvitamin D [25(OH)D] levels were significantly higher in the vitamin D group than in the placebo group (35.4 ± 8.5 ng/mL vs. 18.4 ± 7.3 ng/mL, p < 0.001). There was no difference in HOMA-IR or changes in arterial stiffness (placebo, 21, vitamin D, 24) between the groups.ConclusionsOur data suggest that high-dose vitamin D supplementation might be effective in terms of elevating 25(OH)D levels. However, we identified no beneficial effects on cardiovascular risk in type 2 diabetes, including IR and arterial stiffness.

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BackgroundThe incidence of osteoporosis and its related fractures are expected to increase significantly in the rapidly aging Korean population. Reliable data on the prevalence of this disease is essential for treatment planning. However, sparse data on Korean patients is available.MethodsWe analyzed data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008 to 2010. Bone mineral density (BMD) was measured at the femoral neck and lumbar spine using dual-energy X-ray absorptiometry. Osteopenia and osteoporosis were diagnosed according to the World Health Organization T-score criteria. We analyzed the BMD data of 17,208 people (men, 7,837; women, 9,368).ResultsThe adjusted prevalence of osteoporosis was 7.8% in men versus 37.0% in women. No significant difference was observed in the prevalence of osteopenia between genders (men, 47.0%; women, 48.7%). The prevalence of osteoporosis in men in their 50s was 4.0%, in their 60s was 7.2%, in their 70s was 15.1%, and in their 80s was 26.7%. The figures in women were 15.2%, 36.5%, 62.7%, and 85.8%, respectively. The age group with the maximal BMD differed between genders. In the men, 20s had the highest value in all the skeletal sites. However, in the women, the maximal BMD in the femoral neck, lumbar spine, and the total hip was observed in their 20s, 30s, and 40s, respectively. The onset age of osteoporosis differed between genders. Osteoporosis in the femoral neck began at 55 years in the women and at 60 years in the men.ConclusionThe prevalence of osteoporosis in Korea was significantly high. In addition, the age-related changes in the prevalence of osteoporosis differed according to gender and skeletal site.

Background and PurposeDiabetes is associated with cognitive decline as well as the development of dementia. Although mean blood glucose levels are typically used to assess the status of diabetic patients, glucose variability is also involved in the manifestation of macro- and microvascular complications in this population. Thus, the present study sought to determine whether visit-to-visit glucose variability contributes to cognitive decline in patients with type 2 diabetes.MethodsThe present study assessed 68 patients with type 2 diabetes using several validated neuropsychological measures. All patients had no cerebrovascular disease, history of hypoglycemia, psychiatric conditions, or other medical illnesses. Standard deviations (SDs) and coefficients of variance (CVs) of the patients’ blood glucose (after fasting and 2 hours postprandial; FBS and PP2), and glycated hemoglobin (HbA1c) values were used as indices of glucose variability. The cognitive outcome parameters were transformed with z-scores and entered into a multiple linear regression model that included educational status, age, sex, vascular risk factors, and mean glucose parameters as covariates.ResultsThe mean age of the total patient population was 70.9 years; 46 (67.6%) of the patients were men, and the median follow-up duration at our endocrinology outpatient clinic was 4.8 years. The mean FBS and PP2 glucose levels of the patients were 132 mg/dL and 199 mg/dL, respectively, and the mean HbA1c level was 8.0%. A univariable analysis revealed that only the PP2 value was associated with the Mini-Mental State Examination (MMSE) score, and multivariable analysis revealed that a high SD and/or CV for PP2 glucose were associated with low scores on the Rey Complex Figure Copy test and/or the Verbal Learning Test. Additionally, a high SD and a higher CV for HbA1c level were significantly associated with low MMSE and Digit Span test scores even after adjusting for mean HbA1c values.ConclusionsThe present data indicate that a greater degree of visit-to-visit glucose variability influenced specific types of cognitive function in type 2 diabetic patients independently of mean blood glucose levels. Future studies should focus on whether reductions in glycemic variability will improve the cognitive decline observed in type 2 diabetic patients.

These data suggested that glycemic control, total physical activity, and food intake varied seasonally in Korean T2DM patients. These seasonal variations should be considered in education for glycemic control.