The aim of the present study was to establish a reference interval for homeostasis model assessment of insulin resistance (HOMA‐IR) in a Japanese population based on the C28‐A3 document from the Clinical and Laboratory Standards Institute (CLSI). We selected healthy subjects aged 20–79 years, with fasting plasma glucose < 100 mg/dL, body mass index < 25 kg/m2 and alanine aminotransferase < 31 U/L. HOMA‐IR values were log transformed, values beyond mean ± 3 standard deviations (SD) were truncated, and the mean ± 2 SD of log HOMA‐IR values were taken as the upper and lower reference limits of HOMA‐IR. We selected 2173 subjects as reference individuals, and 2153 subjects were used for analysis. The reference interval for HOMA‐IR was established as between 0.4 and 2.4. This represents the first reference interval study for HOMA‐IR that applies the stringent CLSI C28‐A3 document. HOMA‐IR ≥ 2.5 should be considered a reasonable indicator of insulin resistance in Japanese. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00113.x, 2011)

Objective The objective was to clarify the significance of high high-density lipoprotein cholesterol (HDL-C) levels in the metabolic syndrome (MetS). The evaluation focused on insulin resistance as an indicator of early-stage MetS. Methods and Subjects Of 2705 men who first underwent an annual health check-up at Tokai University Hachioji Hospital, 2129 men were included in this study, after exclusion of those on medication for hypertension, diabetes or dyslipidemia, and those with a prior history of ischemic heart disease, cerebrovascular disease or chronic renal failure. MetS risk factors include the following five parameters: waist circumference, blood pressure, plasma glucose, triglycerides and HDL-C. The correlations between HDL-C and number of MetS risks with homeostasis model assessment of insulin resistance (HOMA-IR) were analyzed. HOMA-IR, number of risks, habits of smoking, exercise and drinking alcohol, stratified by HDL-C levels, were compared in MetS subjects. Results In cases with !2 risk factors, the higher the HDL-C, the lower the HOMA-IR. However, with "3 risk factors for MetS, the HOMA-IR increased when HDL-C was "90 mg/dL. In MetS subjects, the rate of alcohol intake "75 g/day was high when HDL-C was "90 mg/dL. Conclusion In MetS subjects with high HDL-C levels, insulin resistance was increased. Therefore, in persons with high HDL-C levels, it is important to monitor the amount of alcohol consumption and reduce alcohol consumption to <75 g/day.

We investigated the effects of rikkunshito, in combination with a proton pump inhibitor, on symptoms and quality of life in patients with proton pump inhibitor-refractory gastroesophageal reflux disease. The subjects were 47 patients with gastroesophageal reflux disease with residual symptoms such as heartburn following 8 weeks of proton pump inhibitor therapy. We administered these subjects rikkunshito in combination with a proton pump inhibitor for 6–8 weeks. We scored their symptoms of heartburn, fullness, abdominal discomfort, and abdominal pain, and surveyed their quality of life using the Reflux Esophagitis Symptom Questionnaire, comprising questions concerning daily activities, meals (changes in amount and favorite foods), and sleep (getting to sleep and early morning waking). Improvement was seen in all symptoms, and quality of life scores for meals and sleep also improved. These results indicate that combination therapy with rikkunshito and a proton pump inhibitor improves quality of life related to eating and sleep in patients with patients with proton pump inhibitor-refractory gastroesophageal reflux disease.

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