Oral contraceptive use and glucose metabolism in a national sample of women in the united states.

OBJECTIVE: This study was undertaken to determine whether users of oral contraceptives in a nationally representative population of US women had elevated levels of measures of glucose metabolism. STUDY DESIGN: Cross-sectional data from the Third National Health and Nutrition Examination Survey (1988-1994) included hemoglobin A(1c) levels and fasting glucose, insulin, and C-peptide levels. Means were compared among those who had never used oral contraceptives, current users of oral contraceptives, and former users of oral contraceptives, with and without adjustment for potential confounders. RESULTS: The vast majority of current users of oral contraceptives were using low-dose estrogen formulations. The two most common preparations were a triphasic formulation containing 0. 035 mg ethinyl estradiol and 0.5, 0.75, and 1 mg norethindrone (23. 9%) and a monophasic formulation containing 0.035 ethinyl estradiol and 1 mg norethindrone (20.7%). Current users of oral contraceptives did not have elevated values for any of the four measures of glucose metabolism. Hemoglobin A(1c) level and fasting glucose, insulin, and C-peptide levels were not related to duration of current use, age at which use began, or major formulation type. Among women who were former users of oral contraceptives there was no evidence of higher values among those who had recently ceased use. CONCLUSION: Oral contraceptive formulations currently available in the United States are not associated with an adverse glucose metabolic profile.

Diurnal variation in fasting plasma glucose: implications for diagnosis of diabetes in patients examined in the afternoon.

CONTEXT: Current diagnostic criteria for diabetes are based on plasma glucose levels in blood samples obtained in the morning after an overnight fast, with a value of 7.0 mmol/L (126 mg/dL) or more indicating diabetes. However, many patients are seen by their physicians in the afternoon. Because plasma glucose levels are higher in the morning, it is unclear whether these diagnostic criteria can be applied to patients who are tested for diabetes in the afternoon. OBJECTIVES: To document diurnal variation in fasting plasma glucose levels in adults not known to have diabetes, and to examine the applicability to afternoon-examined patients of the current diagnostic criteria for diabetes. DESIGN, SETTING, AND PARTICIPANTS: Analysis of data from the US population-based Third National Health and Nutrition Examination Survey (1988-1994) on participants aged 20 years or older who had no previously diagnosed diabetes, who were randomly assigned to morning (n = 6483) or afternoon (n = 6399) examinations, and who fasted prior to blood sampling. MAIN OUTCOME MEASURES: Fasting plasma glucose levels in morning vs afternoon-examined participants; diabetes diagnostic value for afternoon-examined participants. RESULTS: The morning and afternoon groups did not differ in age, body mass index, waist-to-hip ratio, physical activity index, glycosylated hemoglobin level, and other factors. Mean (SD) fasting plasma glucose levels were higher in the morning group (5.41 [0.01] mmol/L [97.4 ¿0.3¿ mg/dL]) than in the afternoon group (5.12 [0.02] mmol/L [92.4 ¿0.4¿ mg/dL]; P<.001). Consequently, prevalence of afternoon-examined participants with fasting plasma glucose levels of 7.0 mmol/L (126 mg/dL) or greater was half that of participants examined in the morning. The diagnostic fasting plasma glucose value for afternoon-examined participants that resulted in the same prevalence of diabetes found in morning-examined participants was 6.33 mmol/L (114 mg/dL) or greater. CONCLUSIONS: Our results indicate that if current diabetes diagnostic criteria are applied to patients seen in the afternoon, approximately half of all cases of undiagnosed diabetes in these patients will be missed.

Incidence of colorectal carcinoma in the U.S.: an update of trends by gender, race, age, subsite, and stage, 1975-1994.

BACKGROUND: Colon carcinoma incidence rates have risen sharply over the second half of this century, particularly among males and blacks. In the late 1970s, incidence rates among whites began to decline for distant disease. Approximately 10 years later regional disease rates began to fall. The decline in incidence rates among whites largely has been attributed to more widespread colorectal carcinoma screening. However, similar trends by stage in blacks have not been observed. METHODS: The incidence of colorectal carcinoma was evaluated by race, gender, age, and stage of disease for each subsite using data from > 220,000 cases diagnosed between 1975 and 1994 in the U. S. Surveillance, Epidemiology, and End Results program. RESULTS: Recent data have continued to show a decrease in incidence rates of total colorectal carcinoma in whites since the mid-1980s, particularly for the distal colon and rectum. Overall, proximal colon carcinoma rates were higher than distal colon or rectal carcinoma rates throughout the study period. Proximal colon carcinoma rates in blacks were considerably higher than in whites and continued to increase, whereas rates in whites showed signs of declining. The age-specific and stage-specific trends for proximal colon carcinoma in blacks were not consistent with the possibility of earlier disease detection through screening. CONCLUSIONS: Etiologic studies are necessary to understand the large increases in the incidence of proximal colon carcinoma among blacks.

Can physical activity minimize weight gain in women after smoking cessation?

OBJECTIVES: The purpose of this study was to examine prospectively whether exercise can modify weight gain after smoking cessation in women. METHODS: Data were analyzed from a 2-year follow-up period (1986-1988) in the Nurses' Health Study, an ongoing cohort of 121,700 US women aged 40 to 75 in 1986. RESULTS: The average weight gain over 2 years was 3.0 kg in the 1474 women who stopped smoking, and 0.6 kg among the 7832 women who continued smoking. Among women smoking 1 to 24 cigarettes per day, those who quit without changing their levels of exercise gained an average of 2.3 kg more (95% confidence interval [CI] = 1.9, 2.6) than women who continued smoking. Women who quit and increased exercise by between 8 to 16 MET-hours (the work metabolic rate divided by the resting metabolic rate) per week gained 1.8 kg (95% CI = 1.0, 2.5), and the excess weight gain was only 1.3 kg (95% CI = 0.7, 1.9) in women who increased exercise by more than 16 MET-hours per week. CONCLUSIONS: Smoking cessation is associated with a net excess weight gain of about 2.4 kg in middle-aged women. However, this weight gain is minimized if smoking cessation is accompanied by a moderate increase in the level of physical activity.

Cigarette smoking and incidence of chronic bronchitis and asthma in women.

STUDY OBJECTIVE: To examine the relation of smoking habits and development of asthma in a large cohort of US women. DESIGN: Prospective cohort study. PARTICIPANTS: Among 74,072 women, 34 to 68 years of age, who were free of major diseases, we documented 671 incident asthma cases and 798 incident cases of chronic bronchitis during 10 years of follow-up. METHODS: Age-adjusted relative risk estimates for smoking categories were calculated separately for chronic bronchitis and asthma. RESULTS: Risk of chronic bronchitis was significantly higher in current smokers than in never smokers (relative risk [RR] = 2.85; 95% confidence interval [CI] = 2.45 to 3.32) and increased with the number of cigarettes smoked per day (p for trend < 0.0001). Approximately 5 years after quitting, chronic bronchitis risk in past smokers approached that in never smokers. In contrast, current smokers were at significantly lower risk for asthma than women who never smoked (RR = 0.57; 95% CI = 0.46 to 0.71) and women who quit (RR = 0.50; 95% CI = 0.40 to 0.62), possibly because individuals with sensitive airways are less likely to become regular smokers, and smokers who develop respiratory symptoms of any etiology tend to quit. Asthma risk in past smokers initially increased compared with that in never smokers, possibly because of quitting prior to diagnosis in response to symptoms of any etiology, but decreased with time since quitting (p for trend = 0.007); within approximately 5 years, the risk did not differ between past and never smokers. CONCLUSION: These data suggest that smoking in adults may not be an independent cause of asthma but could exacerbate or be perceived as exacerbating asthma symptoms in susceptible individuals.

Menopause, postmenopausal estrogen preparations, and the risk of adult-onset asthma. A prospective cohort study.

We prospectively evaluated the association of hormone replacement therapy and asthma incidence in a cohort of pre- and postmenopausal women 34 to 68 yr of age. During 582, 135 person-years of follow-up between 1980 and 1990, 726 new cases of asthma were documented. Postmenopausal women who were never users of replacement hormones had a significantly lower age-adjusted risk of asthma than premenopausal women (relative risk = 0.65; 95% confidence interval [CI] = 0.46 to 0.92). Among naturally menopausal women, the age-adjusted relative risk of asthma for ever use of postmenopausal hormones was 1.49 (95% CI = 1.10 to 2.00); for current use of hormones (conjugated estrogens with or without progesterone), 1.50 (95% CI = 0.98 to 2.30); and for past use, 1.52 (95% CI = 1.08 to 2.13), compared with never use of hormones. Ever users of 10 or more years' duration had twice the age-adjusted risk of asthma compared with women who never used postmenopausal hormones (95% CI = 1.39 to 2.87). Among current users of conjugated estrogens, there was a positive dose-response demonstrated between daily dose and asthma risk (p for trend = 0.007). While confirmatory studies are warranted, these data suggest that estrogen plays a role in the pathophysiology of asthma and that long-term use and/or high doses of postmenopausal hormone therapy increase subsequent risk of asthma.

A prospective study of diet and adult-onset asthma.

A role for diet in the pathophysiology of asthma may be mediated by altered immune or antioxidant activity with consequent effects on airway inflammation. We evaluated associations between several dietary factors assessed by a semiquantitative food frequency questionnaire, and incidence of asthma over a 10-yr period in 77,866 women 34 to 68 yr of age. Women in the highest quintile of vitamin E intake from diet, but not from supplements, had a risk of 0.53 (95% confidence interval [CI] = 0.33 to 0.86) compared with women in the lowest quintile. This relationship, however, was attenuated when the contribution from nuts, a major source of vitamin E in these data and a possible allergen, was removed (relative risk = 0.74 [0.50 to 1.10], p for trend = 0.007). Positive associations were found for vitamins C and E from supplements, but appeared to be explained by women at high risk of asthma initiating use of vitamin supplements prior to diagnosis. A nonsignificant inverse association with carotene intake was noted, but no clear relations with asthma were demonstrated for intake of linoleic acid or omega-3 fatty acids. These data suggest that antioxidant supplementation and intake of various fats during adulthood are not important determinants of asthma, although vitamin E from diet may have a modest protective effect.

Relation of body fat distribution to reproductive factors in pre- and postmenopausal women.

The cross-sectional relations of several reproductive characteristics with self-reported waist-to-hip circumference ratio were evaluated in 44,487 pre- and postmenopausal women 40 to 65 years of age who were free of cancer, cardiovascular disease, and diabetes. All results were adjusted for age, body mass index, cigarette smoking, physical activity, and alcohol intake. Current use of postmenopausal hormones was associated with a significantly lower waist-to-hip ratio than either past or never use independent of type of menopause (0.778 versus 0.784, p = 0.0001 and 0.787, p = 0.0001, respectively), although associations with type (unopposed estrogens versus combined estrogen and progesterone) and duration of hormone therapy were not noted. Waist-to-hip ratio did not differ between pre- and postmenopausal women, but demonstrated weak positive associations with age at menarche, parity, and age at first birth, and a weak inverse association with past duration of breast-feeding. These data confirm relations of several reproductive factors and use of hormone replacement therapy with body fat distribution. Epidemiologic studies relating body fat distribution to disease outcomes in women should consider these factors as potential confounders.

Relationship of catecholamine excretion to body size, obesity, and nutrient intake in middle-aged and elderly men.

Catecholamine release from sympathetic nerves and the adrenal medulla is influenced by diet under controlled research conditions. To test whether diet affects catecholamine excretion in free-living men, the urinary content of dopamine (DA), epinephrine (Epi), or norepinephrine (NE) was measured in 24-h collections provided by 572 participants of the Normative Aging Study of the Veterans Administration. Average daily intakes of energy and macronutrients were assessed by means of a semiquantitative food frequency questionnaire and sodium intake by quantitation of sodium excretion. Catecholamine excretion was also examined in relation to anthropometric variables. Because DA and Epi excretion were inversely related to age, all subsequent analyses included adjustments for age. Although DA and NE were positively related to measures of body size and fatness, Epi was negatively related to body fatness. Excretion rates of all three catecholamines were directly related to total energy intake and inversely related to energy-adjusted CHO consumption.

Cigarette smoking, dietary intake, and physical activity: effects on body fat distribution--the Normative Aging Study.

Studies have indicated that although smokers weigh less than nonsmokers, smokers have greater waist-to-hip circumference ratios after adjustment for age and body mass index (BMI). The purpose of this investigation was to determine whether factors associated with smoking, such as dietary intake, alcohol intake, and physical activity, modified or confounded the relationship between smoking and body fat distribution. The study used cross-sectional data for 765 men aged 43-85 y from the Normative Aging Study. Current smokers were found to have a greater amount of central adiposity, as represented by the abdomen-to-hip circumference ratio (abdomen-hip ratio), than did former smokers and people who never smoked after adjustment for age, BMI, dietary and alcohol intakes, and physical activity. Multiple-linear-regression analysis revealed that physical activity was negatively associated with and alcohol intake was positively associated with the abdomen-hip ratio. These results suggest a direct effect of smoking on body fat distribution, independent of other smoking-related behaviors.

Relation of obesity and diet to sympathetic nervous system activity.

The hypothesis that dietary intake and obesity stimulate the sympathetic nervous system was investigated in a cross-sectional study of 572 men aged 43-85 years from the Normative Aging Study. Habitus was represented by body mass index, as a measure of overall adiposity, and by the ratio of abdomen-to-hip circumference (abdomen/hip ratio), as a measure of centripetal fat distribution. Sympathetic activity was assessed by measurement of 24-hour urinary norepinephrine excretion. Increased body mass index and total caloric intake were independently associated with increased 24-hour urinary norepinephrine excretion (p = 0.0001 and p = 0.0055, respectively). In addition, mean urinary norepinephrine excretion was higher in subjects classified as either hyperglycemic (serum fasting glucose greater than or equal to 113 mg/dl) and hyperinsulinemic (serum fasting insulin greater than or equal to 19 microIU/ml) (p = 0.0023) or in subjects classified as either hyperglycemic or hyperinsulinemic (p = 0.0063) than the mean urinary norepinephrine excretion in normal subjects. These relations were demonstrated to be independent of age, smoking status, and physical activity. Our results are consistent with the hypothesis that insulin mediates sympathetic stimulation in response to dietary intake and increases sympathetic nervous system activity in the obese.

The relationship of body fat distribution to blood pressure in normotensive men: the normative aging study.

Body fat distribution may be a more specific marker than obesity for risk of cardiovascular disease and diabetes. The relationship between body fat distribution and sitting systolic and diastolic blood pressure was examined in a cross-sectional analysis of 1936 normotensive men aged 21 to 80 years. In this analysis body fat distribution was represented by the ratio of abdomen circumference to hip breadth (denoted as WHbR). Pearson product-moment correlations adjusted for age revealed a positive correlation between WHbR and both systolic and diastolic blood pressure (r = 0.13 and r = 0.14, respectively). In a multiple linear regression model controlling for age, smoking status and body mass index (BMI), WHbR was associated with systolic blood pressure [regression coefficient (standard error) = 3.58 (1.8), P = 0.048)], but had much less of an association with diastolic blood pressure [regression coefficient (standard error) = 1.90 (1.3), P = 0.141]. Further adjustment for alcohol intake decreased the association between WHbR and systolic blood pressure [regression coefficient (standard error) = 2.90 (1.81), P = 0.110]. Body fat distribution, as represented by WHbR was associated with level of systolic blood pressure independently of overall level of obesity (BMI) in normotensive men; adjustment for alcohol intake attenuated the relationship. These data suggest that dietary factors, notably alcohol intake, may influence the effect of body fat distribution on blood pressure.