Inverse association between insulin resistance and gait speed in nondiabetic older men: results from the U.S. National Health and Nutrition Examination Survey (NHANES) 1999-2002.

BACKGROUND: Recent studies have revealed the associations between insulin resistance (IR) and geriatric conditions such as frailty and cognitive impairment. However, little is known about the relation of IR to physical impairment and limitation in the aging process, eg. slow gait speed and poor muscle strength. The aim of this study is to determine the effect of IR in performance-based physical function, specifically gait speed and leg strength, among nondiabetic older adults. METHODS: Cross-sectional data were from the population-based National Health and Nutrition Examination Survey (1999-2002). A total of 1168 nondiabetic adults (> or = 50 years) with nonmissing values in fasting measures of insulin and glucose, habitual gait speed (HGS), and leg strength were analyzed. IR was assessed by homeostasis model assessment (HOMA-IR), whereas HGS and peak leg strength by the 20-foot timed walk test and an isokinetic dynamometer, respectively. We used multiple linear regression to examine the association between IR and performance-based physical function. RESULTS: IR was inversely associated with gait speed among the men. After adjusting demographics, body mass index, alcohol consumption, smoking status, chronic co-morbidities, and markers of nutrition and cardiovascular risk, each increment of 1 standard deviation in the HOMA-IR level was associated with a 0.04 m/sec decrease (p = 0.003) in the HGS in men. We did not find such association among the women. The IR-HGS association was not changed after further adjustment of leg strength. Last, HOMA-IR was not demonstrated in association with peak leg strength. CONCLUSION: IR is inversely associated with HGS among older men without diabetes. The results suggest that IR, an important indicator of gait function among men, could be further investigated as an intervenable target to prevent walking limitation.

Relation of C-reactive protein to stroke, cognitive disorders, and depression in the general population: systematic review and meta-analysis.

Evidence suggests that a high concentration of C-reactive protein (CRP) is a cardiovascular risk factor and an important correlate of cognitive disorders and depression. Recently, population-based studies examining the association between CRP and stroke, cognitive impairment, or depression have been done but have not yet been systematically reviewed. Here we present a systematic review of the associations between CRP and stroke, cognitive impairment, and depression. Hospital or clinic-based studies were excluded because the inferences might not be easily applicable to the general population. 19 eligible studies of CRP were selected: seven for stroke, six for cognitive disorders, and six for depression. Raised CRP concentrations were associated with history of stroke and increased risk of incident stroke. Meta-analysis of studies with long follow-up (>8 years) showed that the risk for stroke in healthy individuals with the highest quartile of CRP concentrations increased nearly 70% compared to those with the lowest quartile. High concentrations of CRP were predictive of cognitive decline and dementia. The relations of CRP to depression were all cross-sectional and were not consistent. We conclude that high concentrations of CRP are associated with increased risk of stroke and cognitive impairment. The association between CRP and depression should be studied prospectively.

A family history of diabetes mellitus is associated with poor glycemic control and increased metabolic risks among people with diabetes: data from the National Health and Nutrition Examination Survey 1999-2004.

BACKGROUND: Several lines of evidence from studies involving both general and non-diabetic populations have shown that a family history of diabetes was associated with an increased risk for cardiovascular diseases and metabolic alterations. However, little is known about the relationship of a family history of diabetes to glycemic control and metabolic risks among people with diabetes. METHODS: We conducted a cross-section study of 946 diabetic adults from the National Health and Nutrition Examination Survey between 1999 and 2004. Familial risk of diabetes was classified as average, moderate, or high. Logistic regression analyses were conducted to determine the association between familial risk of diabetes and poor glycemic control, as defined by A1C > or = 8%. According to stratified levels of familial risk of diabetes, adjusted means of various metabolic risks, including A1C, BMI, lipid profiles, and C-reactive protein, were obtained by using multiple linear regression. RESULTS: Independent of basic demographics, health-related behaviors, use of anti-diabetic medications, diabetes duration, cardiovascular co-morbidities, and various metabolic risks, the odds ratio of poor glycemic control comparing participants with a high familial risk of diabetes to those with an average risk was 1.91 (95% confidence interval 1.02-3.58). In the multivariate analysis, the adjusted means of A1C in participants with high, moderate, and averaged familial risk of diabetes were 7.75%, 7.45%, and 7.25%, respectively (p for trend 0.036). Participants with a high familial risk of diabetes also had higher triglycerides and body mass index (p for trend 0.042 and 0.02, respectively). CONCLUSION: Diabetic adults with a higher familial risk of diabetes have a worse glycemic control, higher BMI, and higher triglycerides. Obtaining family history of the disease is crucial in identifying and targeting high risk diabetic patients who may require more stringent lifestyle changes as well as pharmaceutical intervention.