Insulin resistance predicts mortality in nondiabetic individuals in the U.S.

OBJECTIVE: Insulin resistance is a suspected causative factor in a wide variety of diseases. We aimed to determine whether insulin resistance, estimated by the homeostasis model assessment for insulin resistance (HOMA-IR), is associated with all-cause or disease-specific mortality among nondiabetic persons in the U.S. RESEARCH DESIGN AND METHODS: We determined the association between HOMA-IR and death certificate-based mortality among 5,511 nondiabetic, adult participants of the third U.S. National Health and Nutrition Examination Survey (1988-1994) during up to 12 years of follow-up, after adjustment for potential confounders (age, sex, BMI, waist-to-hip ratio, alcohol consumption, race/ethnicity, educational attainment, smoking status, physical activity, C-reactive protein, systolic and diastolic blood pressure, plasma total and HDL cholesterol, and triglycerides). RESULTS: HOMA-IR was significantly associated with all-cause mortality (adjusted hazard ratio 1.16 [95% CI 1.01-1.3], comparing successive quartiles of HOMA-IR in a linear model and 1.64 [1.1-2.5], comparing the top [HOMA-IR >2.8] to the bottom [HOMA-IR or=25.2 kg/m(2). Subjects in the second, third, and fourth quartile of HOMA-IR appeared to have higher cardiovascular mortality than subjects in the lowest quartile of HOMA-IR. HOMA-IR was not associated with cancer-related mortality. CONCLUSIONS: HOMA-IR is associated with all-cause mortality in the nondiabetic U.S. population but only among persons with normal BMI. HOMA-IR is a readily available measure that can be used in the future to predict mortality in clinical or epidemiological settings.

Is obesity associated with anemia of chronic disease? A population-based study.

Obesity is characterized by chronic, low-grade, systemic inflammation, which, in turn, has been associated with anemia of chronic disease. We hypothesized that obesity may be associated with the features of anemia of chronic disease, including low hemoglobin concentration, low serum iron and transferrin saturation (TS), and elevated serum ferritin. We compared normal-weight to overweight and obese adult participants of the third National Health and Nutrition Examination Survey with respect to hemoglobin concentration and levels of serum iron, TS, and ferritin. Measured BMI was used to categorize participants into normal weight (BMI < 25 kg/m(2), n = 6,059), overweight (BMI 25 to <30 kg/m(2), n = 5,108), mildly obese (BMI 30 to <35 kg/m(2), n = 2,366), moderately obese (BMI 35 to <40 kg/m(2), n = 850), and severely obese (BMI > or = 40 kg/m(2), n = 465). After adjustment for age, gender, menstruation, race/ethnicity, education, alcohol consumption, smoking, blood donation, and dietary iron intake, serum ferritin was progressively higher with increasing BMI category, whereas serum iron and TS were progressively lower. However, compared to normal-weight persons, those in all other higher BMI categories did not have a significant change in hemoglobin concentration after adjustment for the above-mentioned confounders. Overweight and obesity were associated with changes in serum iron, TS, and ferritin that would be expected to occur in the setting of chronic, systemic inflammation. However, overweight and obese persons were not more likely to be anemic compared with normal-weight persons.