Insulin resistance precedes weight loss in adults without diabetes : the Rancho Bernardo Study

High serum iron markers are associated with periodontitis in post-menopausal women: A population-based study (NHANES III)

AIM

To investigate the association between increased serum markers of iron (ferritin and transferrin saturation) and the severity and extent of periodontitis in post-menopausal (PM) women.

MATERIALS AND METHODS

Data from 982 PM women participating in NHANES III were analysed. Exposures were high ferritin (≥300 μg/ml) and transferrin saturation (≥45%). The primary outcome was moderate/severe periodontitis defined according to Centers for Disease Control and Prevention and the American Academy of Periodontology. The extent of periodontitis was also assessed as outcome: proportion of sites affected by clinical attachment loss ≥4 mm and probing depth ≥4 mm. Crude and adjusted prevalence ratio (PR) and mean ratio (MR) were estimated using Poisson regression.

RESULTS

The prevalence of moderate/severe periodontitis was 27.56%. High ferritin was associated with moderate/severe periodontitis in the crude (PR 1.55, p = .018) and in the final adjusted model (PR 1.53, p = .008). High ferritin and transferrin saturation levels were associated with a higher proportion of sites with clinical attachment loss ≥4 mm (p < .05).

CONCLUSIONS

The increasing serum iron markers seem to contribute to periodontitis severity and extent in PM women.

Genetic and environmental associations between insulin resistance and weight-related traits and future weight change

OBJECTIVES

The aims of this study were to investigate the association between initial insulin resistance (IR), weight status, and precedent weight change (PWC) and future weight change and the genetic and environmental contributions affecting these relationships in a prospective cohort of Korean twins and their family members.

METHODS

The PWC (weight change from 20 y of age), baseline body mass index (BMI), baseline homeostasis model assessment of IR (HOMA-IR) score, and future weight change (follow-up interval 3.28 ± 1.32 y) of 1565 adults were assessed. The mixed linear model was applied after adjusting for intrafamilial relationship, age, education, health behaviors, chronic diseases, dietary intake, eating restraint, and menopausal status of women at baseline. A bivariate genetic analysis was performed after adjusting for age and sex.

RESULTS

In the model that simultaneously included all predictors and confounding factors, inverse associations were observed between PWC and baseline HOMA-IR score and future weight change in men, and only baseline BMI was inversely associated with future weight change in women. Men and women with BMI ≥25 kg/m², HOMA-IR score ≥2.5, and PWC greater than or the same as the sex-specific median of PWC were more likely to lose weight than those with the combination of the counterparts. Approximately 63.6% of the correlation between the baseline HOMA-IR score and future weight change was attributed to genetic effects, and 68.4% to 91.3% of the correlations between weight-related traits and future weight change were correlated to environmental effects.

CONCLUSION

An inverse association was observed between the initial IR, weight status, and PWC and future weight change, and genetic or environmental factors contributed to these relationships.

Development of Obesity: The Driver and the Passenger

Obesity has reached epidemic proportions and is one of the greatest challenges for public health in the twenty-first century. The macronutrient composition of diets, in particular the amount and ratio of carbohydrates, fat and protein, have received considerable attention in recent decades due to its potential relevance to the development of obesity and weight loss. The effects of various macronutrients on body weight regulation are still under debate. High-carbohydrate diets, and particularly high-fat diets, have been blamed for the increase in the prevalence of obesity. This paper shows that neither fat nor carbohydrates are fattening per se. Mixed diets with substantial amounts of fat and high-glycemic carbohydrates, like current WDs, are required to promote weight gain and obesity. High-glycemic carbohydrates are the active partner (the "driver"), which promotes fat storage through its insulinogenic effect, while fat is the passive partner (the "passenger") on the way to obesity. Elevated insulin levels (postprandial, but more importantly due to hypersecretion and hyperinsulinemia) promote fat storage and play a key role in obesogenesis and the obesity epidemic. Furthermore, mixed diets high in high-glycemic carbohydrates and fat promote fetal programming, with long-term adverse impacts on the offspring, including insulin hypersecretion, (childhood) obesity and metabolic diseases. Maternal obesity and high weight gain during pregnancy have also been linked to deleterious effects on fetal programming. As the global obesity epidemic increasingly affects women of reproductive age, a significant percentage of fetuses will experience fetal programming with a tendency towards obesity - a self-reinforcing process that further fuels the epidemic. A change in lifestyle and diet composition is needed to prevent or limit the development of obesity and related diseases.

Long-Term Weight Gain Associated With High Omentin Levels at Hospital Discharge Improves Prognosis of Patients Following Acute Heart Failure

A obesity paradox has been described following heart failure (HF). The aim of this study was to analyze the association between food intake-involved adipokines and long-term weight changes. Leptin, adiponectin, and omentin were analyzed in 92 acute HF (AHF) patients at discharge, classified on the basis of weight gains or losses > 6%. The mean follow-up was 256 ± 143 days. Leptin and adiponectin levels were similar among weight groups. However, omentin levels were higher in those patients who had gained weight (16 ± 5 ng/mL) than in those who had lost weight (12 ± 4 ng/mL) or showed no weight change (11 ± 5 ng/mL; p < 0.002). Omentin levels were the best independent predictors for patients with weight gain, who had less mortality and hospital readmission during the follow-up. The association between omentin levels and weight gain might explain part of the obesity paradox in HF.

Ten-year weight gain is associated with elevated fasting insulin levels and precedes glucose elevation

BACKGROUND

Numerous studies have examined the relationship between endogenous insulin and weight change with mixed results. This study examined the relationship between fasting insulin levels, insulin resistance (IR), and 10-year weight change by glycaemic stage.

METHODS

Using data from the US National Health and Nutrition Examination Survey 2011-2014, 3840 participants were divided into 6 groups based on fasting glucose and fasting insulin levels. Fasting insulin concentrations were dichotomized into <25th percentile (normal) and ≥25th percentile (elevated). Ten-year weight change associated with fasting insulin was assessed by glycaemic stage.

RESULTS

Average weight change over a 10-year period was higher in individuals with elevated insulin levels compared to the first quartile (1.40 lbs. vs 11.12 lbs, P < .0001). Across all groups, a 1 μU increase in fasting insulin levels resulted in a 0.52-pound increase in weight (P < .0001). Similarly, an increase in HOMA-IR was associated with increase in weight (1.32 lbs per IR unit, P < .0001). Marginal increases in weight were most pronounced in the normal insulin groups compared to elevated insulin groups and diminished as glycaemic stage progressed.

CONCLUSIONS

Elevated fasting insulin level was positively associated with weight gain. The impact of fasting insulin and IR on weight gain preceded hyperglycaemia and diminished as glycaemic stage progressed.

A longitudinal study of serum insulin and insulin resistance as predictors of weight and body fat gain in African American and Caucasian children

BACKGROUND

The influence of insulin and insulin resistance (IR) on children's weight and fat gain is unclear.

OBJECTIVE

To evaluate insulin and IR as predictors of weight and body fat gain in children at high risk for adult obesity. We hypothesized that baseline IR would be positively associated with follow-up body mass index (BMI) and fat mass.

SUBJECTS/METHODS

Two hundred and forty-nine healthy African American and Caucasian children aged 6-12 years at high risk for adult obesity because of early-onset childhood overweight and/or parental overweight were followed for up to 15 years with repeated BMI and fat mass measurements. We examined baseline serum insulin and homeostasis model of assessment-IR (HOMA-IR) as predictors of follow-up BMI Z-score and fat mass by dual-energy X-ray absorptiometry in mixed model longitudinal analyses accounting for baseline body composition, pubertal stage, sociodemographic factors and follow-up interval.

RESULTS

At baseline, 39% were obese (BMI⩾95th percentile for age/sex). Data from 1335 annual visits were examined. Children were followed for an average of 7.2±4.3 years, with a maximum follow-up of 15 years. After accounting for covariates, neither baseline insulin nor HOMA-IR was significantly associated with follow-up BMI (Ps>0.26), BMIz score (Ps>0.22), fat mass (Ps>0.78) or fat mass percentage (Ps>0.71). In all models, baseline BMI (P<0.0001), body fat mass (P<0.0001) and percentage of fat (P<0.001) were strong positive predictors for change in BMI and fat mass. In models restricted to children without obesity at baseline, some but not all models had significant interaction terms between body adiposity and insulinemia/HOMA-IR that suggested less gain in mass among those with greater insulin or IR. The opposite was found in some models restricted to children with obesity at baseline.

CONCLUSIONS

In middle childhood, BMI and fat mass, but not insulin or IR, are strong predictors of children's gains in BMI and fat mass during adolescence.

Fasting hyperglycemia predicts lower rates of weight gain by increased energy expenditure and fat oxidation rate

CONTEXT

Increased adiposity and insulin resistance are associated with hyperglycemia and previous studies have reported that higher glucoses are associated with lower rates of weight gain. One possible mechanism is via increased energy expenditure (EE).

OBJECTIVE

To assess the relationships between changes in EE during spontaneous weight gain and concomitant changes in glucose levels.

DESIGN AND PARTICIPANTS

Body composition, metabolic, and glycemic data were available from nondiabetic Native Americans who underwent two measurements of 24-h EE during eucaloric feeding in a metabolic chamber (N = 144; time between measurements: 5.0 ± 3.3 years) or resting EE by ventilated hood system during the euglycemic-hyperinsulinemic clamp (N = 261; 4.5 ± 3.2 years). Long-term follow-up data (8.3 ± 4.3 years) for weight and body composition were available in 131 and 122 subjects, respectively.

MAIN OUTCOME MEASURES

Twenty four hour EE and respiratory quotient (RQ), resting (RMR), and sleeping (SMR) metabolic rates, glucose, and insulin levels, basal glucose output (BGO).

RESULTS

Weight gain-associated increase in fasting plasma glucose (FPG) levels was accompanied with decreased 24-h RQ (partial R = -0.24, P = .002) and increased 24-h EE, RMR, SMR, and fat oxidation after accounting for changes in body composition (partial R: 0.12 to 0.19, all P ≤ .05). Upon weight gain, BGO tended to increase (P = .07), while insulin infusion induced a decrease in EE (P = .04). Higher baseline FPG predicted lower rates of future weight gain (partial R = -0.18, P = .04).

CONCLUSIONS

Higher FPG after weight gain was associated with greater-than-expected increase in EE. The rise in BGO and the insulin-induced EE suppression at follow-up indicate that increased hepatic gluconeogenesis may be an important mediator of EE changes associated with weight gain.

The Rancho Bernardo Study: 40 years studying why women have less heart disease than men and how diabetes modifies women's usual cardiac protection

Forty years ago, few cohort studies of cardiovascular disease (CVD) included women and fewer still included diabetes or glycemia as a risk factor. I describe here the Rancho Bernardo Study (RBS), a single-site, >40-year cohort study of sex differences in heart disease and how diabetes modifies women's natural cardioprotection. More than 6000 participants were followed for morbidity and mortality, with nearly 3000 survivors (and death certificates for >85% of decedents). In RBS more than half of diabetes was undiagnosed without an oral glucose tolerance test (OGTT); more women than men had isolated post-challenge hyperglycemia (IPH) as their only glucose evidence of diabetes; men had more diabetes than women, with higher fasting but lower post-challenge glucose levels than women; women with diabetes had more classical CVD risk factors than men; excess risk-factor clustering partially explained how diabetes eradicates female cardioprotection. Post-challenge glucose was a stronger CVD risk factor than fasting glucose. Endogenous insulin was not an independent CVD risk factor in women or men. Men with higher testosterone levels developed less diabetes and had fewer metabolic syndrome components. In men higher total testosterone levels predicted a reduced risk of all-cause and CVD but not cancer mortality. In women both extremes of bioavailable testosterone predicted fatal coronary heart disease but not all-cause mortality. Summary point estimates from large systematic reviews of individual data have replicated most RBS findings. Ongoing research can further clarify how diabetes modifies women's cardioprotection from mid-life to old age.

Central obesity in the elderly is related to late-onset Alzheimer disease

The evidence relating obesity measured with body mass index (BMI) in the elderly to late-onset Alzheimer disease (LOAD) is conflicting. Central obesity in middle age is related to a higher risk of LOAD, but data in the elderly are lacking. We explored whether measures of central obesity, waist circumference, and waist to hip ratio (WHR) were better predictors of LOAD compared with BMI in the elderly. Participants were 1459 persons aged 65 years and older without dementia at baseline, with follow-up, and with anthropometric data from a longitudinal study of aging in New York City. Proportional hazards regression was used for multivariable analyses relating BMI, waist circumference, and WHR to LOAD. There were 145 cases of Alzheimer disease in 5734 person-years of follow-up. Only WHR was related to higher LOAD risk (hazard ratio of the fourth quartile compared with the first=2.5; 95% confidence interval=1.3, 4.7) after adjustment for age, sex, education, ethnic group, Apolipoprotein E-ε4, type 2 diabetes, hypertension, non-high-density lipoprotein-cholesterol, high-density lipoprotein cholesterol, and stroke. Our results support the notion that central obesity is related to a higher risk of LOAD.

The relationship between visceral adiposity and cognitive performance in older adults

BACKGROUND

a direct association between visceral adiposity on abdominal computed tomography (CT) and cognitive performance has not been reported.

OBJECTIVES

to investigate the associations between total and regional adiposity measured with abdominal CT, and cognitive performance in elderly persons and to explore their modification by age.

DESIGN

cross-sectional study.

SETTING

a health promotion centre of a tertiary university hospital.

SUBJECTS

two-hundred and fifty individuals aged 60 years and above who underwent anthropometric measurements, abdominal CT and cognitive testing.

METHODS

adiposity measures included body mass index (BMI), waist circumference and visceral and subcutaneous adiposity by abdominal CT. Poor cognitive performance was defined as Mini-Mental State Examination score being at or below 1 SD of age, sex and education-normative values.

RESULTS

in multivariate logistic regression analyses obesity [odds ratio (OR) 2.61, 95% confidence interval (CI)=1.21-6.01, P=0.015] and being in the top tertile of the visceral adiposity area (OR: 2.58, 95% CI=1.001-6.62, P=0.045) were associated with poor cognitive performance in subjects younger than 70 years, but not in those 70 years and older.

CONCLUSION

high adiposity, particularly visceral adiposity, was associated with poor cognitive functioning in younger elderly persons.

Insulin resistance as a predictor of gains in body fat, weight, and abdominal fat in nondiabetic women: a prospective study

The purpose was to determine the relationship between insulin resistance (IR) and risk of gaining body fat percentage (BF%), body weight, and abdominal fat over 18 months. A prospective cohort study was conducted using a sample of 226 women. IR was assessed using fasting blood insulin and glucose levels to calculate homeostatic model assessment (HOMA). Participants were divided into High (4th quartile) Moderate (2nd and 3rd quartiles), and Low (1st quartile) HOMA categories. BF% was estimated using plethysmography (Bod Pod), weight was measured in a standard swimsuit, and abdominal fat was indexed using the average of two circumferences taken at the umbilicus. Participants wore accelerometers and completed weighed food logs for 7 consecutive days to control for the effect of physical activity (PA) and energy intake, respectively. On average, women in the High HOMA group decreased in BF% (-0.48 ± 3.60), whereas those in the Moderate (0.40 ± 3.66) and Low HOMA (1.17 ± 3.15) groups gained BF% (F = 5.4, P = 0.0211). Changes in body weight showed a similar dose-response relationship (F = 4.7, P = 0.0317). However, baseline IR was not predictive of changes in abdominal fat (F = 0.8, P = 0.3635). Controlling for several covariates had little effect on gains in BF% and weight, but adjusting for initial BF% and/or initial weight nullified changes in BF% and weight across the IR groups. In conclusion, women with High HOMA tend to gain significantly less BF% and weight than women with low or moderate HOMA. The decreased risk appears unrelated to several covariates, except initial BF% and weight levels, which seem to play key roles in the relationships.

Effect of weight loss in adults on estimation of risk due to adiposity in a cohort study

The effect of overweight and obesity on the risk of fatal disease tends to attenuate with age. To evaluate whether this effect is partly attributable to disease-related weight loss, we examined the prebaseline history of weight loss and diseases associated with weight loss among adults enrolled in a cohort study. We conducted an analysis of 7,855 adult cohort members of the Adventist Health Study (AHS) I who had provided anthropometric data on surveys at baseline and 17 years prior to baseline. Among adults in the recommended range of BMI (19-25 kg/m(2)) at baseline we found that: (i) the prevalence of prebaseline weight loss of 5 kg/m(2) from an overweight or obese state was 20.4% and increased with age (12.6% for <65 years; 27.7% for 65-84 years; 36.7% for >85 years) and (ii) prebaseline weight loss of 5 kg/m(2) from an overweight or obese state was associated with diabetes (odds ratio (OR) = 2.91 95% confidence interval (CI) = (2.16, 3.93)), coronary heart disease (OR = 1.84 95% CI = (1.42, 2.40)), and high blood pressure (OR = 1.51 95% CI = (1.26, s1.82)). During 12 years of follow-up, we found evidence that hazard ratios for adiposity can be confounded by disease-related weight loss. Our findings raise the possibility that prebaseline weight loss can confound the estimation of risk due to adiposity at baseline in a cohort study.

Direction of causality between body fat and insulin resistance in children--a longitudinal study (EarlyBird 51)

OBJECTIVE

To investigate the direction of causality in the association between adiposity and insulin resistance in children.

METHODS

Body composition by DEXA, and insulin resistance by HOMA-2 IR were measured annually in 238 children aged from 7-13 years. Longitudinal modelling was used to establish whether baseline and/or trends in adiposity were associated with change in IR or whether, conversely, baseline and/or trends in IR were associated with change in adiposity.

RESULTS

Baseline adiposity was associated with change in IR in the short-term (p < 0.001) but less so in the long-term (p < 0.09) in both genders. Baseline IR was not associated with short-term change in adiposity in either gender (p > 0.42). In the long-term, baseline IR appeared to be positively associated with change in adiposity in boys (p = 0.02) but inversely associated with change in adiposity (the higher the baseline IR, the lower the gain in %fat) in girls (p < 0.001).

CONCLUSIONS

The dominant direction of causality appears to be from adiposity to insulin resistance. In boys, adiposity appears to be both a cause and an effect of IR in the long term. In girls, however, higher insulin resistance appeared to limit further gain in body fat in the long term, an observation consistent with insulin desensitization as an adaptive response to weight gain.

Association of adiponectin with left ventricular mass in blacks: the Jackson Heart Study

BACKGROUND

Blacks have a higher prevalence of left ventricular hypertrophy than whites. Several population-based studies have reported an inverse association between adiponectin and left ventricular mass (LVM); however, the relationship between adiponectin levels and LVM has yet to be defined in blacks. The Jackson Heart Study cohort provides an opportunity to test the hypothesis that the inverse association between adiponectin and LVM may be modified by risk factors common among blacks.

METHODS AND RESULTS

The study population included 2649 black Jackson Heart Study participants (mean age 51±12 years, 63% women, 51% obese, 54% with hypertension, and 16% with diabetes). Multiple linear and spline regression was used to assess the association, with adjustment for demographic, clinical, and behavioral covariates. Among all the participants, there was a statistically significant but modest inverse association between adiponectin and LVM index. Hypertension and insulin resistance emerged as statistically significant effect modifiers of this relationship. The inverse association present among the normotensive participants was explained by obesity measures such as the body mass index. Among participants with both hypertension and insulin resistance, there was a significant direct association between adiponectin and the LVM index after multivariable adjustment (β=1.55, P=0.04, per 1-SD increment in the adiponectin log value).

CONCLUSIONS

The association between serum adiponectin and LVM among blacks in the Jackson Heart Study cohort was dependent on hypertension and insulin resistance status. Normotensive blacks exhibited an inverse adiponectin-LVM association, whereas participants with hypertension and insulin resistance had a direct association.

Body weight, not insulin sensitivity or secretion, may predict spontaneous weight changes in nondiabetic and prediabetic subjects: the RISC study

OBJECTIVE

Previous studies have found that high insulin sensitivity predicts weight gain; this association has not been confirmed. Our aim was to systematically analyze metabolic predictors of spontaneous weight changes.

RESEARCH DESIGN AND METHODS

In 561 women and 467 men from the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) cohort (mean age 44 years, BMI range 19-44 kg/m(2), 9% impaired glucose tolerance) followed up for 3 years, we measured insulin sensitivity (by a euglycemic clamp) and β-cell function (by modeling of the C-peptide response to oral glucose and by acute insulin response to intravenous glucose).

RESULTS

Insulin sensitivity was similar in weight gainers (top 20% of the distribution of BMI changes), weight losers (bottom 20%), and weight stable subjects across quartiles of baseline BMI. By multiple logistic or linear regression analyses controlling for center, age, sex, and baseline BMI, neither insulin sensitivity nor any β-cell function parameter showed an independent association with weight gain; this was true in normal glucose tolerance, impaired glucose tolerance, and whether subjects progressed to dysglycemia or not. Baseline BMI was significantly higher in gainers (26.1 ± 4.1 kg/m(2)) and losers (26.6 ± 3.7 kg/m(2)) than in weight stable subjects (24.8 ± 3.8 kg/m(2), P<0.0001 for both gainers and losers). Baseline waist circumference (or equivalently, BMI or weight) was a positive, independent predictor of both weight gain and weight loss (odds ratio 1.48 [95% CI 1.12-1.97]) in men and (1.67 [1.28-2.12]) in women. In men only, better insulin sensitivity was an additional independent predictor of weight loss.

CONCLUSIONS

Neither insulin sensitivity nor insulin secretion predicts spontaneous weight gain. Individuals who have attained a higher weight are prone to either gaining or losing weight regardless of their glucose tolerance.

Association between insulin resistance and lean mass loss and fat mass gain in older men without diabetes mellitus

OBJECTIVES

To examine the associations between insulin resistance and changes in body composition in older men without diabetes mellitus.

DESIGN

Longitudinal cohort study of older men participating in the Osteoporotic Fractures in Men (MrOS) study.

SETTING

Six U.S. clinical centers.

PARTICIPANTS

Three thousand one hundred thirty-two ambulatory men aged 65 and older at baseline.

MEASUREMENTS

Baseline insulin resistance was calculated for men without diabetes mellitus using the homeostasis model assessment of insulin resistance (HOMA-IR). Total lean, appendicular lean, total fat, and truncal fat mass were measured using dual energy X-ray absorptiometry scans at baseline and 4.6 ± 0.3 years later in 3,132 men with HOMA-IR measurements.

RESULTS

There was greater loss of weight, total lean mass, and appendicular lean mass and less gain in total fat mass and truncal fat mass with increasing quartiles of HOMA-IR (P<.001 for trend). Insulin-resistant men in the highest quartile had higher odds of 5% or more loss of weight (odds ratio (OR)=1.88, 95% confidence interval (CI)=1.46-2.43), total lean mass (OR=2.09, 95% CI=1.60-2.73) and appendicular lean mass (OR=1.57, 95% CI=1.27-1.95) and lower odds of 5% or more gain in total fat mass (OR=0.56, 95% CI=0.45-0.68) and truncal fat mass (OR=0.52, 95% CI=0.42-0.64) than those in the lowest quartile. These findings remained significant after accounting for age, site, baseline weight, physical activity, and change in physical activity. These associations were also independent of other metabolic syndrome features and medications.

CONCLUSION

Greater lean mass loss and lower fat mass gain occurred in insulin-resistant men without diabetes mellitus than in insulin-sensitive men. Insulin resistance may accelerate age-related sarcopenia.

Insulin resistance influences weight loss in non-obese women who followed a home-based exercise program and slight caloric restriction

This study aimed to evaluate the influence of insulin resistance status on weight changes in non-obese women who followed a home-based exercise program and slight caloric restriction over a period of 12 months. Middle-aged (25-45 year), non-obese (body mass index of 23-29.9 kg/m(2)) women were randomly assigned to control (CG) or home-based exercise group (HB). The HB group received a booklet explaining the physical exercises to be practiced at home at least three times per week (40 min/session). Both groups were required to follow a small energy restriction of 100-300 calories per day. For the analysis, women were stratified in two groups according to baseline insulin sensitivity: NIR (non-insulin resistant; n = 121) and IR (insulin resistant; n = 64). Women classified as IR at baseline had greater weight loss after 12 months of follow-up (-1.6 kg vs. -1.1 kg; p = 0.01), and HB exercise helped to reduce weight only among NIR women (-1.5 vs. -0.7; p = 0.04); no differences were observed between intervention groups for IR women (-1.5 vs. -1.7; p = 0.24). There were no differences between IR and NIR groups for lipid profile after adjustment for weight changes. Insulin resistance facilitated weight loss, and home-based exercise promoted greater weight loss only in non-insulin resistance women.

Higher incremental insulin area under the curve during oral glucose tolerance test predicts less food intake and weight gain

OBJECTIVE

To investigate the correlation of peripheral insulin concentrations with food intake and body weight.

DESIGN

Cross sectional and longitudinal clinical study: we investigated the association of peripheral insulin concentrations in response to an oral glucose tolerance test (OGTT) with subsequent measures of ad libitum food intake and body weight change.

SUBJECTS

Food intake analysis: Pima Indians (n=67, 63% male; body mass index (mean ± s.d.) 34.2 ± 9.4 kg m(-2)) with normal glucose regulation (NGR; fasting glucose <5.6 mmol l(-1) and 2-h glucose <7.8 mmol l(-1)) participated in a study of ad libitum food intake measured over 3 days by an automated vending machine system. Weight change analysis: Pima Indians with NGR (n=339) who also participated in a longitudinal study of risks for type 2 diabetes and had follow-up weights.

RESULTS

Food intake analysis: incremental area under the curve (iAUC) for insulin during the OGTT was negatively associated with mean daily ad libitum energy intake (DEI) (r=-0.26, P=0.04), calories consumed as percent weight-maintenance energy needs (%WMEN) (r=-0.38, P=0.002) and carbohydrate intake (gram per day) (r=-0.35, P=0.005). Adjustment for age and sex attenuated the association of iAUC with DEI (P=0.06) not with %WMEN and carbohydrate intake (P=0.005, P=0.008). Weight change analysis: after adjustment for age, sex, follow-up time and initial body weight, higher insulin iAUC predicted less absolute and percent weight change (β=-6.9, P=0.02; β=-0.08, P=0.008, respectively).

CONCLUSIONS

In healthy Pima Indians with NGR, higher plasma iAUC during an OGTT predicted lower food intake and carbohydrate consumption and less weight gain. These data indicated a role for peripheral insulin as a negative feedback signal in the regulation of energy intake and body weight.

Diet quality and weight gain among black and white young adults: the Coronary Artery Risk Development in Young Adults (CARDIA) Study (1985-2005)

BACKGROUND

Little is known about the long-term health consequences of following the 2005 Dietary Guidelines for Americans (DGA; Washington, DC: US Government Printing Office, 2005).

OBJECTIVE

The objective was to examine the longitudinal association between diets consistent with the 2005 DGA and subsequent weight gain.

DESIGN

We used data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a cohort of black and white men and women aged 18-30 y at baseline who attended ≤7 examinations from 1985-1986 to 2005-2006 (n = 4913). We created a 100-point Diet Quality Index (2005 DQI) to rate participants' diets based on meeting the 2005 DGA key recommendations. Longitudinal models of weight gain were adjusted for physical activity, smoking, energy intake, age, education, sex, and initial body mass index (BMI) and included interaction terms of DQI by race and initial BMI (if statistically significant).

RESULTS

We found effect modification by race (likelihood ratio test, P < 0.03 in all models). The mean adjusted 20-y weight change was +19.4 kg for blacks and +11.2 kg for whites with high diet quality (DQI >70) and +17.8 for blacks and +13.9 for whites with a DQI <50 (P < 0.05). In race-specific Cox models (with interaction terms for DQI × initial BMI, P < 0.05), a 10-point increase in DQI score was associated with a 10% lower risk of gaining 10 kg in whites with an initial BMI (in kg/m(2)) <25 but with a 15% higher risk in blacks with baseline obesity (P < 0.001).

CONCLUSIONS

Our findings do not support the hypothesis that a diet consistent with the 2005 DGA benefits long-term weight maintenance in American young adults. Greater need for attention to obesity prevention in future DGAs is warranted.

Preoperative weight gain might increase risk of gastric bypass surgery

BACKGROUND

Weight loss improves the cardiovascular and metabolic risk associated with obesity. However, insufficient data are available about the health effects of weight gain, separate from the obesity itself. We sought to determine whether the changes in body weight before open gastric bypass surgery (OGB) would have a significant effect on the immediate perioperative hospital course.

METHODS

A retrospective chart review of 100 consecutive patients was performed to examine the effects of co-morbidities and body weight changes in the immediate preoperative period on the hospital length of stay and the rate of admission to the surgical intensive care unit (SICU).

RESULTS

Of our class III obese patients undergoing OGB, 95% had ≥1 co-morbid condition and an overall SICU admission rate of 18%. Compared with the patients with no perioperative SICU admission, the patients admitted to the SICU had a greater degree of insulin resistance (homeostatic model analysis-insulin resistance 10.8 ± 1.3 versus 5.9 ± 0.5, P = .001), greater serum triglyceride levels (225 ± 47 versus 143 ± 8 mg/dL, P = .003), and had gained more weight preoperatively (.52 ± .13 versus .06 ± .06 lb/wk, P = .003). The multivariate analyses showed that preoperative weight gain was a risk factor for a longer length of stay and more SICU admissions lasting ≥3 days, as were a diagnosis of sleep apnea and an elevated serum triglyceride concentration.

CONCLUSION

The results of the present retrospective study suggest that weight gain increases the risk of perioperative SICU admission associated with OGB, independent of the body mass index. Sleep apnea and elevated serum triglyceride levels were also important determinants of perioperative morbidity. In view of the increasing epidemic of obesity and the popularity of bariatric surgical procedures, we propose that additional clinical and metabolic research focusing on the understanding of the complex relationship among obesity, positive energy balance, weight gain, and perioperative morbidity is needed.

Relationship of glucose regulation to changes in weight: a systematic review and guide to future research

Although weight gain and obesity are risk factors for poor glucose regulation, the relationship, if any, of glucose regulation to changes in weight is not well understood. The purpose of this study was to conduct a systematic review of research examining the relationship of glucose regulation to changes in weight in human-based studies and to provide guidelines for future research in this area. We searched electronic databases and reference sections of relevant articles, including both diabetic and non-diabetic populations, to locate all the literature published before February 2010, and then conducted a systematic review across studies to compare the research designs and findings. The 22 studies meeting our criteria for review generally supported the relationship of glucose regulation to changes in weight. Three studies reported that poor glucose regulation is associated with weight gain; 12 studies concluded that poor glucose regulation is associated with weight loss; 5 showed complex relationships depending on age, sex, or race/ethnicity; and 2 suggested no relationship. The diverse findings may imply that the direction (negative or positive) of the relationship may depend on specific conditions. More research focused on different subpopulations may provide more definitive information supplemental to the current preliminary findings. Recommendations regarding future research in this particular area are provided in the discussion.

Association between adiposity in midlife and older age and risk of diabetes in older adults

CONTEXT

Adiposity is a well-recognized risk factor for type 2 diabetes among young and middle-aged adults, but the relationship between body composition and type 2 diabetes is not well described among older adults.

OBJECTIVE

To examine the relationship between adiposity, changes in adiposity, and risk of incident type 2 diabetes in adults 65 years of age and older.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study (1989-2007) of 4193 men and women 65 years of age and older in the Cardiovascular Health Study. Measures of adiposity were derived from anthropometry and bioelectrical impedance data at baseline and anthropometry repeated 3 years later.

MAIN OUTCOME MEASURE

Incident diabetes was ascertained based on use of antidiabetic medication or a fasting glucose level of 126 mg/dL or greater.

RESULTS

Over median follow-up of 12.4 years (range, 0.9-17.8 years), 339 cases of incident diabetes were ascertained (7.1/1000 person-years). The adjusted hazard ratio (HR) (95% confidence interval [CI]) of type 2 diabetes for participants in the highest quintile of baseline measures compared with those in the lowest was 4.3 (95% CI, 2.9-6.5) for body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]), 3.0 (95% CI, 2.0-4.3) for BMI at 50 years of age, 4.2 (95% CI, 2.8-6.4) for weight, 4.0 (95% CI, 2.6-6.0) for fat mass, 4.2 (95% CI, 2.8-6.2) for waist circumference, 2.4 (95% CI, 1.6-3.5) for waist-hip ratio, and 3.8 (95% CI, 2.6-5.5) for waist-height ratio. However, when stratified by age, participants 75 years of age and older had HRs approximately half as large as those 65 to 74 years of age. Compared with weight-stable participants (+/-2 kg), those who gained the most weight from 50 years of age to baseline (> or = 9 kg), and from baseline to the third follow-up visit (> or = 6 kg), had HRs for type 2 diabetes of 2.8 (95% CI, 1.9-4.3) and 2.0 (95% CI, 1.1-3.7), respectively. Participants with a greater than 10-cm increase in waist size from baseline to the third follow-up visit had an HR of type 2 diabetes of 1.7 (95% CI, 1.1-2.8) compared with those who gained or lost 2 cm or less.

CONCLUSION

Among older adults, overall and central adiposity, and weight gain during middle age and after the age of 65 years are associated with risk of diabetes.

Prospective investigation of metabolic characteristics in relation to weight gain in older adults: the Hoorn Study

The objective of this investigation was to determine the relation between baseline glucose, insulin, adiponectin, and leptin levels and subsequent 6-year weight and waist change in older men and women without diabetes in a prospective cohort study. Participants were 1,198 Dutch men and women without diabetes who were aged 50-77 years when baseline metabolic and anthropometric measurements were evaluated (1989-1991). Approximately 6 years later, body weight and waist circumference were re-measured at a follow-up examination (1996-1998). Metabolic variables (fasting plasma glucose, 2-h postchallenge plasma glucose, homeostasis model assessment of insulin resistance (HOMA-IR), adiponectin, and leptin) were evaluated as predictors of changes in weight and waist circumference. Postchallenge plasma glucose (mmol/l) significantly predicted less gain in both weight and waist circumference (beta = -0.28 kg, s.e. = 0.11; beta = -0.31 cm, s.e. = 0.14, respectively) during follow-up. Leptin (microg/l) significantly predicted greater increases in weight (beta = 0.29 kg, s.e. = 0.07) and waist (beta = 0.16 cm, s.e. = 0.08) among men and in waist among women (beta = 0.06 cm, s.e. = 0.02). Fasting plasma glucose (mmol/l) predicted an increase in waist among women (beta = 1.59 cm, s.e. = 0.63), but not in men (beta = -0.74 cm, s.e. = 0.55). Adiponectin and insulin did not predict weight or waist change. The authors conclude that lower postchallenge plasma glucose and higher fasting leptin levels significantly predicted long-term increases in weight and waist circumference. In contrast, measures of insulin resistance and adiponectin were not associated with weight change in this cohort of older persons without diabetes.

Adiposity, type 2 diabetes, and Alzheimer's disease

This manuscript provides a comprehensive review of the epidemiologic evidence linking the continuum of adiposity and type 2 diabetes (T2D) with Alzheimer's disease (AD). The mechanisms relating adiposity and T2D to AD may include hyperinsulinemia, advanced products of glycosylation, cerebrovascular disease, and products of adipose tissue metabolism. Elevated adiposity in middle age is related to a higher risk of AD but the data on this association in old age is conflicting. Several studies have shown that hyperinsulinemia, a consequence of higher adiposity and insulin resistance, is also related to a higher risk of AD. Hyperinsulinemia is a risk factor for T2D, and numerous studies have shown a relation of T2D with higher AD risk. The implication of these associations is that a large proportion of the world population may be at increased risk of AD given the trends for increasing prevalence of overweight, obesity, hyperinsulinemia, and T2D. However these associations may present a unique opportunity for prevention and treatment of AD. Several studies in the prevention and treatment of T2D are currently conducting, or have planned, cognition ancillary studies. In addition, clinical trials using insulin sensitizers in the treatment or prevention of AD are under way.

Adiposity and Alzheimer's disease

PURPOSE OF REVIEW

Alzheimer's disease is the most common form of dementia. There are no known preventive or curative measures. There is increasing evidence for the role of total adiposity, usually measured clinically as BMI, and central adiposity, in Alzheimer's disease. This topic is of enormous public health importance given the global epidemic of high adiposity and its consequences.

RECENT FINDINGS

Salient publications in 2007 and 2008 showed that (a) central adiposity in middle age predicts dementia in old age; (b) the relation between high adiposity and dementia is attenuated with older age; (c) waist circumference in old age, a measure of central adiposity, may be a better predictor of dementia than BMI; (d) lower BMI predicts dementia in elderly people; and (e) weight loss may precede dementia diagnosis by decades, which may explain seemingly paradoxical findings.

SUMMARY

The possibility that high adiposity increases Alzheimer's disease risk is alarming given global trends of overweight and obesity in the general population. However, prevention and manipulation of adiposity may also provide a means to prevent Alzheimer's disease. Treatment of weight loss in Alzheimer's disease may also be important but is beyond the score of this review.

Socioeconomic position and risk of short-term weight gain: prospective study of 14,619 middle-aged men and women

Background

The association between socioeconomic position in middle age and risk of subsequent, short-term weight gain is unknown. We therefore assessed this association in a prospective population based cohort study in Norfolk, UK.

Methods

We analysed data on 14,619 middle-aged men and women (aged between 40–75 at baseline) with repeated objective measures of weight and height at baseline (1993–1997) and follow up (1998–2000).

Results

During follow up 5,064 people gained more than 2.5 kg. Compared with the highest social class, individuals in the lowest social class had around a 30% greater risk of gaining more than 2.5 kg (OR 1.29; 95% CI 1.11–1.51; p for trend = 0.002). This association remained statistically significant following adjustment for sex, age, baseline BMI, smoking, and follow up time (OR 1.25; CI 1.07–1.46; p for trend <0.001). We also found no material difference between unadjusted models and those including all confounders and potential mediators.

Conclusion

Individuals of low socioeconomic position are at greatest risk of gaining weight during middle age, which is not explained by classical correlates of socioeconomic position and risk factors for obesity.

Adiposity, hyperinsulinemia, diabetes and Alzheimer's disease: an epidemiological perspective

The objective of this manuscript is to provide a comprehensive review of the epidemiologic evidence linking the continuum of adiposity, hyperinsulinemia, and diabetes with Alzheimer's disease. The mechanisms for these associations remain to be elucidated, but may include direct actions from insulin, advanced products of glycosilation, cerebrovascular disease, and products of adipose tissue metabolism. Elevated adiposity in middle age is related to a higher risk of Alzheimer's disease. The evidence relating adiposity in old age to Alzheimer's disease is conflicting. Several studies have shown that hyperinsulinemia, a consequence of higher adiposity and insulin resistance, is also related to a higher risk of Alzheimer's disease. Hyperinsulinemia is a risk factor for diabetes, and numerous studies have shown a relation of diabetes with higher Alzheimer's disease risk. Most studies fail the take into account the continuum linking these risk factors which may result in underestimation of their importance in Alzheimer's disease. The implication of these associations is that a large proportion of the world population may be at increased risk of Alzheimer's disease given the trends for increasing prevalence of overweight, obesity, hyperinsulinemia, and diabetes. However, if proven causal, these associations also present a unique opportunity for prevention and treatment of Alzheimer's disease.

Pathophysiologic mechanisms of obesity and related metabolic disorders: an epidemiologic study using questionnaire and serologic biomarkers

BACKGROUND

It is still unclear whether individuals with the same degree of obesity but different weight histories since young adulthood have different insulin concentration, prevalence of metabolic syndrome components and their clustering.

METHODS

A cross-sectional study was conducted on 3,399 (for weight difference analysis) and 1,879 (for weight fluctuation analysis) Japanese men aged 40-59 years. Weight difference was calculated by subtracting the recalled weight at about 25 years old from the current weight. The root mean square error around the slope of weight on age (weight - RMSE) was calculated by a simple linear regression model, in which the subject's actual weights at ages 20, 25, 30, 40 years and 5 years prior to the study, as well as current weight, were dependent variables against the subject's age as the independent variable. Each metabolic syndrome component was defined as follows: serum triglycerides ≥150 mg/dL; HDL-cholesterol <40 mg/dL; fasting glucose ≥110 mg/dL; and blood pressure ≥140/90 mm Hg.

RESULTS

Those who gained <10%, <20%, or 20% or more in weight had a significantly higher than unity odds ratio of having two or more metabolic syndrome components in relation to those whose weight remained stable: 1.28 (95% confidence interval: 0.95-1.73), 2.49 (1.91-3.24), and 5.30 (3.97-7.07), respectively. Weight-RMSE was significantly and positively associated with fasting insulin concentration independent of current weight, weight-slope or other lifestyle-related factors.

CONCLUSIONS

Metabolic syndrome components would likely tend to cluster more in individuals with large weight gain on a physiologic basis characterized by high fasting insulin concentration. Furthermore, weight fluctuation was suggested to increase the risk of fasting hyperinsulinemia.

The metabolic syndrome

The metabolic syndrome is a cluster of symptoms associated with insulin resistance and known to precede the onset of type 2 diabetes. Overweight and obesity contribute significantly to the development of the metabolic syndrome. In fact, weight loss has a huge impact in decreasing the symptoms associated with the metabolic syndrome. Several studies have demonstrated that just by losing 7% to 10% of initial body weight is sufficient to have improvement in waist circumference, dyslipidemias (elevated triglycerides and low high-density-lipoprotein cholesterol), trunk fat, and plasma glucose. This paper underlines the importance of weight loss and type of diet in reversing the symptoms of the metabolic syndrome.

Adiposity and Alzheimer's disease

The objective of this manuscript is to provide a comprehensive review of the relation between adiposity and Alzheimer's disease (AD), its potential mechanisms, and issues in its study. Adiposity represents the body fat tissue content. When the degree of adiposity increases it can be defined as being overweight or obese by measures such as the body mass index. Being overweight or obese is a cause of hyperinsulinemia and diabetes, both of which are risk factors for AD. However, the epidemiologic evidence linking the degree of adiposity and AD is conflicting. Traditional adiposity measures such as body mass index have decreased validity in the elderly. Increased adiposity in early or middle adult life leads to hyperinsulinemia which may lead to diabetes later in life. Thus, the timing of ascertainment of adiposity and its related factors is critical in understanding how it might fit into the pathogenesis of AD. We believe that the most plausible mechanism relating adiposity to AD is hyperinsulinemia, but it is unclear whether specific products of adipose tissue also have a role. Being overweight or obese is increasing in children and adults, thus understanding the association between adiposity and AD has important public health implications.

The Collaborative Study of Obesity and Diabetes in Adults (CODA) project: meta-analysis design and description of participating studies

The Collaborative Study of Obesity and Diabetes in Adults (CODA) project was formed to establish an international database of studies of abdominal obesity and type 2 diabetes mellitus (T2DM), and to provide analyses of these associations using individual participant data (IPD) meta-analytic techniques. The collaboration involves obtaining raw data from existing studies. The main objectives of the collaboration are to assess which simple anthropometric indices most closely predict the risk of T2DM in adults, and to investigate ethnicity and other factors that potentially modify that prediction. A second task related to primary prevention of diabetes subsequently evolved, the CODA-2 project, and is concerned with population-based methods to identify people most likely to benefit from diabetes interventions. This article describes the meta-analysis design and the studies involved. The collaboration currently has 37 studies enrolled, providing data on 260,000 participants. The proposed IPD meta-analyses will help resolve several outstanding issues in diabetes.

Measures of adiposity and dementia risk in elderly persons

BACKGROUND

Studies relating adiposity to dementia are conflicting. We explored the associations of body mass index (BMI), (calculated as weight in kilograms divided by the square of height in meters) waist circumference, and weight change to dementia, probable Alzheimer disease, and dementia associated with stroke (DAS).

DESIGN

Persons without dementia were followed up for 5 years; 893 persons had BMI data, 907 had waist circumference data, and 709 had a second weight measurement. Dementia was ascertained using standard methods. Cox proportional hazards regression was used for analyses using follow-up as time to event, adjusting for demographics and apolipoprotein E-epsilon4 status.

RESULTS

Compared with persons in the first quartile of BMI, persons in the third quartile had a lower dementia and Alzheimer disease risk and persons in the second quartile had a lower DAS risk. The association between BMI and dementia resembled a U shape in those younger than 76 years, while dementia risk decreased with higher BMI in those 76 years and older. The fourth quartile of waist circumference was related to a higher DAS risk in the whole sample, and to dementia and Alzheimer disease in persons younger than 76 years. Weight loss was related to a higher dementia and DAS risk, and weight gain was related to a higher DAS risk only.

CONCLUSIONS

The prospective association between adiposity and dementia differs depending on the anthropometric measure used, and is modified by age. This may explain previous conflicting reports.

Long-term effects of leisure time physical activity on risk of insulin resistance and impaired glucose tolerance, allowing for body weight history, in Danish men

AIMS

To determine if the level of leisure time physical activity (LTPA) in young adulthood in obese and non-obese men reduces the risk of insulin resistance (IR) and impaired glucose tolerance (IGT) in middle age, and if such an effect is explained by the current level of LTPA, or by the body mass index (BMI) history preceding and subsequent to the assessment of LTPA.

METHODS

Longitudinal study of groups of obese and randomly selected non-obese men identified at around age 19, and re-examined at mean ages of 32, 44 and 51. BMI was measured at all four examinations. LTPA was assessed by self-administrated questionnaires at the last three examinations. IR and the presence of IGT was determined by an oral glucose tolerance test at the last examination.

RESULTS

LTPA in young adulthood reduced the risk of IR and IGT in middle age throughout the range of BMI. Adjustment for the BMI history preceding and subsequent to the assessment of LTPA attenuated the association with IR and IGT, but active men remained at low risk of IR and IGT. Adjustment for subsequent and current levels of LTPA, smoking habits, alcohol intake, educational level and family history of diabetes had no notable influence on the results.

CONCLUSION

LTPA appears to reduce the risk of IR and IGT, an effect which is not explained by the current level of physical activity, and only partially explained by the BMI history preceding and subsequent to the assessment of LTPA.

Low insulin-like growth factor-II levels predict weight gain in normal weight subjects with type 2 diabetes

PURPOSE

Insulin-like growth factor (IGF)-I and IGF-II are important in the regulation of metabolism and growth. We previously reported in normoglycemic individuals of normal weight that low circulating IGF-II predicts future weight gain. We subsequently investigated whether such relationships persisted in circumstances of type 2 diabetes.

METHODS

In 224 subjects with type 2 diabetes we assessed the association between baseline IGF-II levels and risk of weight gain (>2.0 kg) at the 5-year follow-up.

RESULTS

At follow-up, 90 participants (40.2%) gained more than 2.0 kg in body weight. For subjects (body mass index <26) at baseline, mean IGF-II levels were significantly lower in those who gained more than 2 kg in weight than in subjects of stable weight, 454 ng/mL (95% confidence interval 349-559) versus 620 ng/mL (534-705) (F=7.4, P=.01). For this subgroup low circulating IGF-II at baseline strongly correlated with weight gain (Spearman rho=-0.52, P <.001). With increasing weight, the relationship no longer prevailed. Logistic regression showed that for body mass index less than 26, individuals at baseline for each 100 ng/mL increase in baseline IGF-II there was a 47% decreased risk of gaining 2.0 kg or more in weight. Adjustment for treatment group did not materially alter this relationship. There was no difference in baseline IGF-II by treatment group. There was no difference between the group with weight gain and the group with stable weight in those who additionally received insulin or sulfonylurea treatment in the 5 years between the baseline visit and the follow-up.

CONCLUSIONS

In subjects of normal weight with type 2 diabetes, baseline IGF-II concentration is inversely related to future weight gain, independent of treatment effect, strengthening the putative role for IGF-II in regulating fat mass. We propose that IGF-II measurement has potential utility in this group for targeting such individuals for early intervention.

Spectrum of insulin sensitivity in the Korean population

The aims of the present study were to (1) examine the range of values for insulin sensitivity measures such as fasting serum insulin, homeostasis model assessment (HOMA), and quantitative insulin sensitivity check index (QUICKI) and (2) to identify cutoffs for indirect indexes of insulin sensitivity such as insulin, HOMA, and QUICKI that confer increased risk of metabolic syndrome in a large sample of Korean adults. The total number of study subjects involved was 83186. All of them presented for a routine health status checkup at the Kangbuk Samsung Hospital between January 2003 and December 2004, and none of them was currently taking medication for hypertension, diabetes, or dyslipidemia. We used 3 measures of insulin sensitivity: the fasting serum insulin, the HOMA, and the QUICKI. The age- and sex-adjusted prevalence of metabolic syndrome was examined by tenths of the distribution of each index of insulin. The fasting serum insulin, HOMA, and QUICKI were compared by using receiver operating characteristic curves. The fasting serum insulin ranged from 1.71 to 70.40 microU/mL, with the 25th percentile = 5.97, the median = 7.69, and the 75th percentile = 9.82. The HOMA ranged from 0.34 to 17.72, with the 25th percentile = 1.33, the median = 1.74, and the 75th percentile = 2.27. The QUICKI ranged from 0.112 to 0.202, with the 25th percentile = 0.146, the median = 0.152, and the 75th percentile = 0.158. The insulin, HOMA, and QUICKI values at the point on the receiver operating characteristic curve closest to the ideal of 100% sensitivity and 100% specificity for detecting the presence of metabolic syndrome were 9.7 microU/mL, 2.43, and 0.145, respectively. In conclusion, these findings describe the spectrum of insulin sensitivity in Korean adults. This study is the first attempt to determine cutoff values for indirect indexes of insulin sensitivity such as insulin, HOMA, and QUICKI that confer an increased risk of metabolic syndrome. These findings may be useful for evaluating insulin resistance, particularly in epidemiological studies.

Two measures of insulin sensitivity provided similar information in a U.S. population

BACKGROUND AND OBJECTIVE

Two methods for measuring insulin sensitivity, fasting plasma insulin (FPI) and homeostasis model assessment (HOMA) have been proposed for use in large epidemiological research and clinical practice. This project describes the range of observed values of the HOMA and FPI in a large sample of the U.S. population.

METHODS

We used fasting plasma glucose and insulin values from the Third National Health and Nutrition Survey (NHANES III) to identify the FPI and HOMA values. For both FPI and HOMA, higher values indicate lower insulin sensitivity.

RESULTS

Among 6,511 participants without treated diabetes mellitus, FPI ranged from 1.8 to 175.8 microU/mL, with 25th percentile=6.7, median=9.3, 75th percentile=13.3, and mean+/-1 SD=11.2+/-7.5; HOMA ranged from 0.3 to 52.6 (mmol)(microU)/L(2), with 25th percentile=1.5, median=2.2, 75th percentile=3.3, and mean+/-SD=2.8+/-2.4.

CONCLUSION

These findings describe the spectrum of insulin sensitivity and may be useful in helping physicians develop a clinical understanding of the dynamic range of both FPI and HOMA measures.

Prevalence and Determinants of Impaired Glucose Metabolism in Frail Elderly Patients: The Belgian Elderly Diabetes Survey (BEDS)

BACKGROUND

Although diabetes in elderly persons is generally type 2, the metabolic abnormalities associated with aging suggest that elderly persons may differ from younger persons with type 2 diabetes. In addition, nonobese elderly persons with type 2 diabetes show a marked impairment in insulin release accompanied by mild insulin resistance, whereas obese elderly persons have marked insulin resistance in the presence of "adequate" levels of insulin. Other factors that could adversely affect glucose tolerance in aging include drug use, associated disease, and other stressful conditions commonly encountered in geriatric inpatients units. The authors' objectives in this study were 1) to prospectively assess the prevalence of glucose homeostasis abnormalities among elderly hospitalized patients and the degree to which it reflects abnormalities in insulin secretion or insulin sensitivity using homeostasis model assessment of fasting glucose, insulin, and C-peptide; and 2) to define the social, functional, pathologic, and nutritional characteristics of persons with impaired glucose tolerance or diabetes.

METHODS

Ninety-eight patients underwent a comprehensive geriatric assessment. Determinants of glucose homeostasis were assessed using the homeostasis model assessment, which provides estimates of beta-cell function (%B) and insulin sensitivity (%S).

RESULTS

Twelve patients (12%) had fasting glucose concentrations greater than 110 mg/dl. Four patients had impaired fasting glucose levels greater than 110 mg/dl but less than 126 mg/dl (IFG group), and 8 patients had levels greater than 126 mg/dl (type 2 diabetes group). Except for a higher proportion of women in the IFG-diabetes group, the latter did not exhibit significant differences in functional, morbidity, or nutritional characteristics compared with the normal glucose tolerance group. The entire cohort (n=98) presented with a mean (+/-SD) %B of 71%+/-47% and a mean %S of 208%+/-198%. Compared with the normal glucose tolerance group, the IFG-diabetes group had a fasting glycemia level of 142+/-24 mg/dl (vs 92+/-9 mg/dl), a %B of 43%+/-21% (vs 74%+/-45%), and a mean %S of 126%+/-113% (vs 219%+/-205%).

CONCLUSIONS

These data confirm the high prevalence of impaired glucose metabolism among elderly people, although the usual risk factors were not significantly increased. Marked beta secretory defects seem to be the rule, whereas a significant degree of insulin resistance is unusual.

Insulin resistance and weight gain in postmenopausal women of diverse ethnic groups

OBJECTIVE

This study was conducted to examine the influence of insulin resistance on weight change in postmenopausal women of various ethnic groups.

SUBJECTS

Data were obtained from 3389 women (60% White, 20% Black, 12% Hispanic, and 8% Asian/Pacific Islander), ages 50-79, enrolled in either the Women's Health Initiative Clinical trial or Observational Study, whose blood samples were selected randomly from the full cohort of 161 809 women for analyses.

MEASUREMENTS

Glucose, insulin, and lipids were measured on fasting serum samples drawn at baseline and after 3 y of follow-up. Weight, height, waist circumference, and blood pressure were measured. Physical activity and energy intake were assessed via questionnaire. Insulin resistance was estimated using the HOMA (homeostasis model) calculation.

RESULTS

Average age was 62 y, average BMI (body mass index) was 27.4 kg/m2, and average weight change was a gain of 0.4 kg in 3 y. In a multivariate analysis, insulin resistance and insulin concentrations were independent predictors of increases in weight in White women (P=0.002 and 0.004, respectively) and in the combined group (P=0.027 and 0.039). For the whole group, after adjustment for other covariates, those in the highest quartile of insulin resistance gained 0.4 kg in 3 y, whereas those in the lowest quartile lost 0.06 kg. Similar trends were found for insulin resistance and weight gain in Hispanic and Asian/Pacific Islander women, but they did not reach statistical significance. In Black women, no relation was seen between either insulin or insulin resistance and weight change. A significant interaction between obesity and insulin resistance was observed (P=0.002 for White women and 0.032 for the whole group), so that there is weight gain with increasing insulin resistance in the leaner women, but weight loss with increasing insulin resistance in the most obese.

CONCLUSION

Insulin resistance appears to be a predictor of weight gain in postmenopausal women, except for the most obese women. The effect is more pronounced in women who have a lower BMI, and the effect was not seen in the Black women who as a group had a higher BMI.

Augmenting leptin circadian rhythm following a weight reduction in diet-induced obese rats: short- and long-term effects

The current study sought to examine whether leptin injections following a weight reduction in diet-induced obese rats would reduce both the enhanced food intake and body weight (BW) regain observed during the refeeding phase. Female Wistar rats (n = 100, 20 per group) were divided into 5 groups: (1) LEP rats were fed a high-fat (HF) diet (35% wt/wt) for 8 weeks to induce obesity and were then food-restricted (50% ad libitum) with a fortified high-fat diet for 2 weeks to induce a 20% BW loss. These rats were then refed the HF diet ad libtum for another 11 weeks. They were given leptin injections (200 microg/kg BW, twice daily, intraperitoneally ) for 19 days concomitant with the onset of refeeding. (2) SAL rats were treated in the same manner as LEP rats except that they were given saline injections; (3) PF rats were treated like SAL rats except that they were pair-fed with the LEP rats; (4) HFC rats were fed HF diet ad libitum; and (5) LFC rats were fed a low-fat (LF) diet (AIN-93M) ad libitum. Ten rats from each group were killed after leptin treatment and at the end of the study. Food and caloric intakes were monitored, and body composition and plasma glucose, insulin, and leptin levels were assessed at death. Leptin injections after a weight reduction briefly reduced energy intake during the first week only. After 19 days of treatment and to the end of the study, LEP and SAL rats were similar in energy intake, BW (LEP: 393 +/- 11.2 g, SAL: 371 +/- 14.1; difference not significant [NS]) and total body fat percent (LEP: 19.3 +/- 1.5, SAL: 17.6 +/- 1.5; NS). Leptin treatment induced hyperinsulinemia and insulin resistance. All of the metabolic abnormalities observed at the end of treatment period disappeared at the end of the study (8 weeks post-leptin injection). We conclude that bolus leptin injections to manipulate leptin circadian rhythm in diet-induced obese rats after a weight reduction caused temporary insulin resistance and hyperinsulinemia, and were ineffective in influencing food intake, BW, and fat content. Leptin resistance was evident following 1 week of treatment in this study. Leptin treatment had no effect on body fat content both short-term and long-term. Exogenous leptin treatment may, in the long run, increase leptin resistance in diet-induced obese animals. Hence, long-term leptin treatment may not be beneficial to obese individuals consuming a HF diet.

Insulin resistance as a modifier of the relationship between dietary fat intake and weight gain

OBJECTIVE

To investigate whether insulin resistance modifies the rate of weight gain associated with a high percent of energy intake from dietary fat.

DESIGN

Longitudinal, observational population study.

SUBJECTS

A total of 782 nondiabetic Hispanic and non-Hispanic white free-living adult residents of the San Luis Valley in Colorado.

MEASUREMENTS

Subjects were seen up to three times over a 14-y period. Weight, height, fasting insulin and glucose, diet by 24 h recall, and self-reported physical activity were collected at each visit.

RESULTS

Percentage of energy intake from dietary fat was positively associated with weight gain over time (P=0.0103). High intake of dietary fat was more strongly related to weight gain in women than in men, and in those with lower total energy intake levels. The relationship between weight change and relative macronutrient intake also varied by baseline insulin sensitivity (P=0.0025). Weight gain over time in individuals with relative insulin resistance at baseline, as measured by QUICKI, was the greatest among those who consumed a higher percent of energy from fat.

CONCLUSION

Percentage of total intake from dietary fat predicts weight change independent of total energy intake. Nondiabetic, insulin-resistant individuals are particularly susceptible to the weight gain associated with high levels of dietary fat intake. Further investigation into the relationship between insulin resistance, diet, and weight gain is warranted.

Waist circumference is a better predictor than body mass index of coronary heart disease risk in overweight premenopausal women

Waist circumference (WC) has been postulated to have stronger associations with biomarkers of coronary heart disease (CHD) than BMI. In this study, we measured the level of activity by determining steps walked per day and select biomarkers for CHD risk in 80 overweight or obese (BMI = 25-37 kg/m(2)) premenopausal women to evaluate whether these biomarkers are associated with WC or BMI. The plasma biomarkers measured, using samples from women who had fasted for 12 h, were lipids, apolipoproteins (apo), LDL peak diameter, LDL susceptibility to oxidation, glucose, leptin, and insulin. We identified subjects with the metabolic syndrome (11%) and insulin resistance (30%) to further distinguish subjects at increased risk for CHD. Both BMI and WC were positively correlated with insulin (r = 0.376 and 0.384, respectively, P < 0.05) and leptin (r = 0.614 and 0.512, respectively, P < 0.01) and negatively correlated with the number of steps taken per day (r = -0.245 and -0.354, respectively, P < 0.05). In addition, WC had positive correlations with diastolic blood pressure (r = 0.250, P < 0.05), plasma triglycerides (TG) (r = 0.270, P < 0.05), and apo C-III (r = 0.240, P < 0.05). Women with BMI > or = 30 kg/m(2) or WC > 88 cm had significantly higher leptin concentrations than women having a BMI < 30 kg/m(2) or a WC < or = 88 cm; women with WC > 88 cm also had higher diastolic pressure (P < 0.05), and higher plasma TG (P < 0.05) and apo C-III (P < 0.05) concentrations than those with WC < or = 88. In addition, subjects with the higher WC walked an average of 1000 fewer steps per day (P < 0.01). These results suggest that WC is a stronger predictor of CHD risk than BMI and is more closely associated with the level of exercise in premenopausal women.

Aging-related attenuation of EGF receptor signaling is mediated in part by increased protein tyrosine phosphatase activity

As fibroblasts near senescence, their responsiveness to external signals diminishes. This well-documented phenomenon likely underlies physiological deterioration and limited tissue regeneration in aging individuals. Understanding the underlying molecular mechanisms would provide opportunities to ameliorate these situations. A key stimulus for human dermal fibroblasts are ligands for the epidermal growth factor receptor (EGFR). We have shown earlier that EGFR expression decreases by about half in near senescent fibroblasts (Shiraha et al., 2000, J. Biol. Chem. 275 (25), 19343-19351). However, as the cell responses are nearly absent near senescence, other aging-related signal attenuation changes must also occur. Herein, we show that EGFR signaling as determined by receptor autophosphorylation is diminished over 80%, with a corresponding decrease in the phosphorylation of the immediate postreceptor adaptor Shc. Interestingly, we found that this was due at least in part to increased dephosphorylation of EGFR. The global cell phosphotyrosine phosphatase activity increased some threefold in near senescent cells. An initial survey of EGFR-associated protein tyrosine phosphatases (PTPases) showed that SHP-1 (PTPIC, HCP, SHPTP-1) and PTPIB levels are increased in parallel in these cells. Concomitantly, we also discovered an increase in expression of receptor protein tyrosine phosphatase alpha (RPTPalpha). Last, inhibition of protein tyrosine phosphatases by sodium orthovanadate in near senescent cells resulted in increased EGFR phosphorylation. These data support a model in which, near senescence, dermal fibroblasts become resistant to EGFR-mediated stimuli by a combination of receptor downregulation and increased signal attenuation.

Low circulating IGF-II concentrations predict weight gain and obesity in humans

Results from experimental and gene-association studies suggest that IGF-II may influence body weight regulation and that individuals with low IGF-II levels may be more susceptible to weight gain and obesity. We therefore assessed the association between circulating concentrations of IGF-II and subsequent weight gain and progression to obesity. Participants in this study were 463 nonobese men and women aged between 45 and 60 years with normal glucose tolerance and with metabolic and anthropometric assessments at baseline and follow-up clinic visits. We examined the association between baseline concentrations of fasting serum IGF-II and risk of gaining > or =2.5 kg body wt or developing obesity using unconditional logistic regression. A total of 217 participants gained > or =2.5 kg body wt, and 29 developed obesity after >4 years of follow-up. In multivariate analysis, baseline IGF-II levels were significantly lower in participants who subsequently gained weight compared with individuals who remained stable or lost weight (P = 0.010). Similarly, individuals who developed obesity had lower baseline IGF-II levels (P = 0.006). Relatively higher IGF-II levels were also associated with a reduced risk of gaining weight (P for trend across quintiles of IGF-II = 0.006). Our data suggest that circulating IGF-II levels may play a role in body weight regulation and development of obesity in men and women with normal glucose tolerance.

Association between weight fluctuation and fasting insulin concentration in Japanese men

OBJECTIVE

To investigate whether long-term weight fluctuation is associated with the fasting serum insulin concentration.

DESIGN AND SUBJECTS

Weight histories of 1932 male Japanese workers aged 40-59 y were analyzed in relation to their current fasting serum insulin concentration.

MEASUREMENTS

Individual weight fluctuation was calculated by root mean square error (RMSE) along the linear regression line of weight measured at five to six different ages.

RESULTS

The mean RMSE and fasting insulin concentration were 1.22 kg and 4.5 microU/ml, respectively. The multivariate adjusted insulin level became higher with the increase in weight fluctuation. Subanalysis stratified by current body mass index (BMI) showed that the multivariate adjusted insulin level in individuals in the top quartile of fluctuation was 4.3 microU/ml, against 3.9 microU/ml in those in the bottom quartile (P=0.018, analysis of covariance (ANCOVA)) in the normal weight subgroup with current BMI below 25 kg/m(2). In the overweight subgroup with BMI 25 kg/m(2) or above, the level was 6.9 microU/ml in individuals in the top quartile and 6.2 microU/ml in those in the bottom quartile (P=0.054, ANCOVA).

CONCLUSION

The results suggest that weight fluctuation increases the risk of developing hyperinsulinemia. Prospective observations together with measurement of changes in adiposity are needed for confirmation.

Insulin and the "thrifty" woman: the influence of insulin during pregnancy on gestational weight gain and postpartum weight retention

OBJECTIVES

To test Neel's hypothesis among pregnant women: a high maternal insulin concentration in early pregnancy increases the risk of weight gain, overweight, and obesity among nondiabetic, low-income gravidas of racial and ethnic minority groups from Camden, New Jersey.

METHODS

Fasting insulin was obtained from 461 gravidas at entry to prenatal care. Insulin quartile was related to rate of gestational weight gain and excess weight gain during pregnancy (> or = 90th percentile) and to retained weight and excess weight retention at 4-6 weeks postpartum (> or = 90th percentile). The relationship between excess retained weight and excessive insulin increase (> or = 90th percentile) was also examined.

RESULTS

Compared with gravidas with an insulin concentration in the lowest three quartiles, gravidas with the highest insulin quartile had a significantly higher rate of gestational weight gain (nonobese women only) and average weight retained postpartum (all women). Compared with an insulin concentration in the lowest three quartiles, the highest insulin quartile was associated with a 2.05-fold (95% confidence interval [CI] = 1.07-3.93) risk of an excessive rate of gestational weight gain and a 3.58-fold (95% CI = 1.87-6.84) risk of excess weight retained postpartum. Excess weight retained postpartum was linked to a 2.63-fold (95% CI = 1.00-6.89) risk of an excessive increase in insulin concentration postpartum.

CONCLUSIONS

Our results support Neel's hypothesis and suggest that a high maternal insulin concentration is associated with increased gestational weight gain and increased weight retention postpartum. High insulin concentration may contribute to pregnancy-related changes in weight and thus may be linked to maternal overweight and obesity postpartum as well as to future risk of gestational and Type 2 diabetes mellitus.