Brian D Cox

A cross-sectional study of dietary patterns with glucose intolerance and other features of the metabolic syndrome

Previous epidemiological studies have demonstrated relationships between individual nutrients and glucose intolerance and type 2 diabetes, but the association with the overall pattern of dietary intake has not previously been described. In order to characterize this association, 802 subjects aged 40-65 years were randomly selected from a population-based sampling frame and underwent a 75 g oral glucose-tolerance test. Principal component analysis was used to identify four dietary patterns explaining 31.7% of the dietary variation in the study cohort. These dietary patterns were associated with other lifestyle factors including socio-economic group, smoking, alcohol intake and physical activity. Component 1 was characterized by a healthy balanced diet with a frequent intake of raw and salad vegetables, fruits in both summer and winter, fish, pasta and rice and low intake of fried foods, sausages, fried fish, and potatoes. This component was negatively correlated with central obesity, fasting plasma glucose, 120 min non-esterified fatty acid and triacylglycerol, and positively correlated with HDL-cholesterol. It therefore appears to be protective for the metabolic syndrome. Component 1 was negatively associated with the risk of having undiagnosed diabetes, and this association was independent of age, sex, smoking and obesity. The findings support the hypothesis that dietary patterns are associated with other lifestyle factors and with glucose intolerance and other features of the metabolic syndrome. The results provide further evidence for the recommendation of a healthy balanced diet as one of the main components of chronic disease prevention.

Undiagnosed glucose intolerance in the community : the isle of Ely diabetes project

The Isle of Ely Diabetes Project is a prospective population‐based study of the aetiology and pathogenesis of Type 2 diabetes mellitus. Between 1990 and 1992, 1156 subjects aged between 40 and 65 years underwent a standard 75 g oral glucose tolerance test (OGTT). A total of 1122 individuals who were not known to have diabetes completed the test and were classified according to WHO criteria; 51 subjects (4.5%) had previously undiagnosed diabetes and 188 (16.7%) had impaired glucose tolerance. The subjects with newly diagnosed glucose intolerance were significantly older, more obese, and shorter than those with normal glucose tolerance. Blood pressure, cholesterol, triglyceride, and LDL‐cholesterol concentrations were elevated and HDL‐cholesterol levels were lower among those with abnormal rather than normal glucose tolerance. In multiple regression analyses stratified by gender and including age, body mass index, and the waist‐hip ratio as covariates, there were significant differences between those with normal and abnormal glucose intolerance in blood pressure, triglyceride, and HDL‐cholesterol, but not total or LDL‐cholesterol. In both male and female subjects, height had a significant independent negative association with the plasma glucose at 120 min after administration of oral glucose (standardized β coefficient = ‐0.12, p<0.01).

Ventilatory function and winter fresh fruit consumption in a random sample of British adults.

The relation between ventilatory function and the reported frequency of consumption of fresh fruit and fruit juice was studied among 1502 lifelong non-smokers and 1357 current smokers aged 18-69 with no history of chronic respiratory disease. Forced expiratory volume in one second (FEV1) was assessed by turbine spirometry. As winter fruit consumption was more widely dispersed than summer consumption and few subjects ate fruit more frequently in the winter, winter fruit consumption was taken as an indicator of habitual (year round) consumption. After adjustment for sex, age, height, cigarette consumption, region of residence, and household socioeconomic group, FEV1 was associated with winter fruit consumption. The mean adjusted FEV1 among those who never drank fresh fruit juice and ate fresh fruit less than once a week during the winter was 78 ml lower (95% confidence interval 24-132 ml) than the mean for the other subjects. A similar difference was found in all age-sex groups and among both current smokers and lifelong non-smokers. Antioxidant and other actions of vitamin C may protect against pulmonary emphysema, or reduce bronchoconstrictor responses to environmental pollutants.

Frequent Salad Vegetable Consumption Is Associated with A Reduction in the Risk of Diabetes Mellitus

This cross-sectional study was undertaken to investigate the association between the reported frequency of consumption of vegetables and fruits, the choice of staple carbohydrate, and glucose intolerance. One thousand one hundred twenty-two subjects aged 40-64 years in a population-based study underwent an oral glucose tolerance test, and their food consumption was assessed using a food-frequency questionnaire. The crude prevalence of undiagnosed non-insulin-dependent diabetes mellitus (NIDDM) was 4.5%, and that of impaired glucose tolerance (IGT) 16.8%. The age-standardized prevalence rates were 2.3 and 11.2%, respectively. Frequent consumption of vegetables throughout the year was inversely associated with the risk of having NIDDM (odds ratio [OR] = 0.16; 95% confidence interval [CI] = 0.04-0.69). This association was maintained after adjustment for age, gender, and family history. Vegetable consumption during the summer months had a much weaker inverse association with the risk of having NIDDM that failed to reach statistical significance. A nonsignificant inverse association between frequent consumption of fruits and NIDDM was observed. Frequent self-reported pasta and rice consumption was associated with a reduction in the risk of having IGT and NIDDM. (OR = 0.62, 95% CI = 0.44-0.87, and OR = 0.51, 95% CI = 0.27-0.99, respectively) but this relationship was not independent of age. Whether these associations reflect specific effects of particular nutrients or are a reflection of the patterning of lifestyle factors remains to be determined.

Height and glucose tolerance in adult subjects

SummaryIn a prospective study concerning the pathogenesis of impaired glucose tolerance and Type 2 (non-insulindependent) diabetes mellitus, 346 subjects with no clinical history of diabetes were given a standard 75 g oral glucose tolerance test. The expected positive associations between 120-min plasma glucose concentration and age and body mass index were observed in both sexes and between 120-min plasma glucose and waist/hip ratio in male subjects. An unexpected negative correlation was found between 120-min plasma glucose and height in both sexes (r = − 0.23, (95% confidence interval, − 0.38− − 0.07) p<0.007 for male subjects and r = − 0.24, (− 0.37− − 0.11) p<0.006 for female subjects). These negative associations with height remained significant after controlling for age and body mass index in male subjects but not in female subjects. In the latter a highly significant negative relationship of height with age was recorded (r = − 0.33, (− 0.45− − 0.20) p<0.0001). Comparison between individuals with impaired glucose tolerance and control subjects matched for sex, age and body mass index showed that subjects with impaired glucose tolerance are significantly shorter. Mean (± SEM) height in the male subjects with impaired glucose tolerance (n = 29) was 173.4 ± 1.1 cm vs 176.9 ± 1.3 cm in control subjects, p = 0.02. In the female subjects(n = 39)mean(±SEM)height was 159.4±1.0 cm vs 162.4±1.0 cm in control subjects, p = 0.02. The negative relationship between height and glucose tolerance is a new epidemiological observation which has not been previously reported. One possible reason for this is that the most commonly used anthropometric index, body mass index, eliminates height as an independent analytical variable.

Cigarette smoking is not associated with hyperinsulinemia: Evidence against a causal relationship between smoking and insulin resistance

Previous reports of a relationship between cigarette smoking and hyperinsulinemia and insulin resistance provide an important possible mechanism by which smoking could be associated with the metabolic cardiovascular syndrome and hence with ischemic heart disease. However, few previous studies have been able to adjust for all the possible confounding factors related both to smoking and to insulin resistance. Therefore, we examined this association in a population-based cohort study of 1,122 individuals aged 40 to 65 years who underwent a 75-g oral glucose tolerance test with specific measurement of insulin, 32,33-split proinsulin, and intact proinsulin concentrations. Physical activity was quantified using the Paffenbarger questionnaire, and smoking status and alcohol consumption were determined using the Health and Lifestyle Survey questionnaire; 17.4% of the population were current smokers and 32.4% were ex-smokers. Current smoking was associated with reduced overall obesity as indicated by the body mass index (BMI) but an increase in central adiposity as measured by the waist to hip ratio (WHR). There were also significant associations between cigarette smoking and the pattern of alcohol intake and physical inactivity. In unadjusted analyses, current smoking was associated with lower fasting and 120-minute insulin and also 120-minute glucose compared with levels in nonsmokers. Adjustment for confounding by age and BMI reduced these differences, but they were increased by adjustment for central obesity. We conclude from this study that a causal relationship between cigarette smoking and insulin resistance is unlikely.

The development of cardiovascular disease in relation to anthropometric indices and hypertension in British adults.

OBJECTIVE: To examine the predictive ability of simple anthropometric indices for the development of cardiovascular disease (CVD) over seven years in British adults, and the influence of hypertension on these associations.DESIGN: Longitudinal study of the development of CVD (morbidity or mortality) over a seven year period in a random stratified sample of British adults who were respondents in the 1984–1985 Health and Lifestyle Survey (HALS1) and who were seen again in 1991–1992 (HALS2) or who had died by then.METHODS: Face-to-face interviews at HALS1 and HALS2 recorded socio-demographic, health and lifestyle details followed by measurements of height, weight, waist circumference and blood pressure (BP). The quintiles of body mass index (BMI), waist circumference, waist : height ratio (WHTR) and height were calculated for those aged between 35 and 75 y, at HALS1. Dates and causes of death were recorded. Logistic regression was used to estimate the odds ratios (OR) of developing CVD in 1284 men and 1570 women, aged 35–75 y who were free of known CVD, cancer and diabetes at HALS1.RESULTS: By HALS2, 316 respondents in the qualifying population had developed CVD, 114 of whom were dead. There were linear trends in the development of CVD (adjusted for age and smoking) for all the men from the lowest to the highest quintile of WHTR (P=0.034), but not for waist circumference (P=0.095), or BMI (P>0.2). Excluding the hypertensive men increased the significance of the trend for WHTR (P=0.005) and waist circumference (P=0.027). The significant interactions with hypertension for WHTR (P<0.001), waist circumference (P=0.006) and BMI (P=0.044) showed that there was an increasing incidence of CVD with increasing adiposity in non-hypertensive men but, in men with treated hypertension, although the overall incidence of CVD was higher, the relationship with adiposity was inverse.In the women, there were no significant linear trends for waist circumference, WHTR or BMI. Quintile estimates were more consistent with J-shaped curves with the lowest risk in the second quintile. Excluding the hypertensive women, increased the significance of these trends. In normotensive women, there was a significant quadratic trend (P=0.039) for the association between the incidence of CVD and the quintiles of waist circumference, but no associations for WHTR or BMI. For waist circumference there was weak evidence of an interaction with hypertension (P=0.053).CONCLUSIONS: For the men, indices involving waist circunference, particularly WHTR, had stronger linear associations with the log odds of CVD development than BMI. The interactions with hypertension were significant for WHTR, waist circunferenceand also BMI. In women, none of the indices was linearly associated with the log odds of CVD development, but there was a significant J-shaped curve for waist circumference and evidence of an interaction with hypertension. These results suggest that studies in which hypertensives are included, but in which possible hypertension interactions are overlooked, important hypertensive-specific associations between anthropometric indices and CVD development may be masked. Men on anti-hypertensive medication with the lowest central adiposity, experienced higher short-term CVD risk than those with greater central adiposity.

Association of anthropometric indices with elevated blood pressure in British adults

OBJECTIVE: To investigate which of six anthropometric indices was most strongly associated with elevated blood pressure and frank hypertension in a representative population sample of young and middle-aged British adults. SUBJECTS: A representative random sample of British adults (2712 men and 3279 women) aged between 18 and 64 y, who were resident in England, Scotland and Wales, were studied in the 1984–85 Health and Lifestyle Survey. MEASUREMENTS: Following an interview where demographic, health and lifestyle details were recorded, measurements of height, weight and waist and hip circumference were made by a nurse at a home visit, where blood pressure and medication to control blood pressure were also recorded. BMI and the ratios of waist circumference to height (WHTR) and waist circumference to hip (WHR) were calculated. Respondents with a blood pressure above 140 mm Hg (systolic) and/or 90 mm Hg (diastolic) or who were being treated for hypertension were classified as having elevated blood pressure. RESULTS: For men and women aged 18–39 and 40–64 y the prevalence of elevated blood pressure increased across the quintiles of BMI, weight, waist, WHTR and WHR was P<0.001 for each, with waist and WHTR having the highest odds ratios. Waist and height adjusted for each other were independently related to the prevalence of elevated blood pressure in 40–64 y old men and women. Height, on its own, was inversely related (P<0.05) only in the 40–64 y old men.  The age adjusted partial correlations between systolic and diastolic blood pressure measurements and the measurements of BMI, weight, waist, WHTR and WHR were close and significant, P<0.001 for each. The ranking and significance of the correlations were hardly affected by excluding the treated hypertensives. CONCLUSIONS: The prevalence of elevated blood pressure was associated with quintiles of BMI, waist, WHTR, WHR and weight, with WHTR and WHR having the highest odds ratios. Waist and height were independently related to the prevalence of elevated blood pressure.

Carbon monoxide levels in the breath of smokers and nonsmokers: effect of domestic heating systems.

Breath and ambient (room) carbon monoxide (CO) levels were measured in a random sample of 168 adults in their own homes. The levels of breath CO in the 69 smokers ranged from 3 ppm to over 100 ppm, 74% being above 10 ppm; mean levels in the 99 nonsmokers were lower than in the smokers, 79% being below 6 ppm. In the remaining 21% of nonsmokers with higher breath levels than expected, the ambient CO was also found to be elevated, ranging up to 38 ppm. A close correlation in the nonsmokers was found between the breath and ambient CO levels (r = 0.952, p less than 0.001). The rooms with the elevated ambient CO levels (above 5 ppm) were those which, at the time of testing, were being heated by gas radiant heaters, open fires or stoves. The maximum ambient CO in the rooms of smokers with non CO generating heating was 16 ppm. The results suggest that many people, both smokers and nonsmokers, may be at risk from CO generated by certain domestic heating systems and that nonsmokers are far more likely to be exposed to high levels of CO from these sources than from being in a room with a heavy smoker. Poor ventilation associated with the current trend towards excluding all draughts is likely to exacerbate the situation for both smokers and nonsmokers.

Frequent consumption of red meat is not risk factor for cancer.

Editor—Headlines such as “Big meat eaters cancer warning” ( Daily Mail , 13 September) have appeared in advance of the publication of the Department of Healths report on diet and cancer.1 2 A prospective study, however, analysed data from a nationwide random stratified sample of British adults to determine the relation between diet and cancer and found a protective role for fruit and salads but no evidence that frequent consumption of meat is a risk factor for cancer. Details of dietary habits (including the usual frequency of consumption …