Body surface area is positively associated with ankle-brachial index.

BACKGROUND: Ankle-brachial index (ABI) measurement is a widely used diagnostic test for lower extremity artery disease. Previously, a larger body surface area (BSA) has been associated with lower blood pressure and lower 2-h post-load glucose concentrations in the oral glucose tolerance test. Our aim was to evaluate whether BSA has an impact on ABI and the prevalence of lower ABI values. METHODS: ABI measurements were performed on 972 subjects aged 45 to 70 years at high cardiovascular disease (CVD) risk. Subjects with previously diagnosed kidney disease, CVD, and diabetes were excluded. Their BSA was calculated by the Mosteller formula. Study subjects were divided into five BSA levels corresponding to 12.5th, 25th, 25th, 25th, and 12.5th percentiles of the total distribution. Effect modification by BSA in ABI between sexes was derived from a four-knot restricted cubic splines regression model. RESULTS: After adjustments for age, sex, pulse pressure, glucose regulation, waist circumference, alcohol intake, smoking status, leisure-time physical activity and medication, BSA level had a positive linear relationship with ABI (p for linearity <0.001). When BSA was less than 2.0 m2, there was no difference between the sexes, but when BSA was higher than 2.0 m2, men had higher ABI. CONCLUSION: BSA shows a positive linear relationship with ABI in CVD risk subjects without manifested CVD. The difference in ABI between men and women is modified by BSA and is appreciable when BSA is larger than 2.0 m2.

Body surface area may explain sex differences in findings from the oral glucose tolerance test among subjects with normal glucose tolerance.

BACKGROUND AND AIMS: Current guidelines on prediabetes and diabetes (T2D) recommend to regularly perform an oral glucose tolerance test (OGTT) on subjects at risk of T2D. However, it is not known why women tend to have relatively higher 2-h post-load plasma (2hPG) glucose concentrations during OGTT than men. The aim of the present study is to investigate if there are sex differences in fasting plasma glucose (FPG) and 2hPG concentrations in relation to body size in apparently healthy non-diabetic subjects with normal glucose tolerance. We hypothesized that sex differences in glucose tolerance are physiological and related to different body surface area (BSA) in men and women. METHODS AND RESULTS: A 2-h 75 g OGTT was performed on 2010 subjects aged 45-70 years. Their BSA was calculated using the Mosteller formula. Men and women were separately divided into five BSA levels. Within the normal 2hPG range, women had higher mean 2hPG concentrations during the OGTT than men in all BSA levels estimated by sex-standardized BSA (p for linearity < 0.001). BSA adjusted for age, waist circumference, leisure-time physical activity, and smoking, showed an inverse association with 2hPG concentration in both sexes. Mean FPG concentrations were higher in men than in women. CONCLUSIONS: Body size has a negative inverse association with 2hPG concentration in an OGTT even within a physiological plasma glucose range. This may cause underestimation of glucose disorders in individuals with larger BSA and overestimation in individuals with smaller BSA when using an OGTT.

Blood pressure load per body surface area is higher in women than in men.

Many unexplained sex differences have been observed in blood pressure (BP) related morbidity. However, there has been little research about the most obvious difference between men and women-body size. Given that blood vessels are organs of tubular shape, we hypothesized that correction of BP for body surface area (BSA), a two-dimensional measurement of body size, would allow comparison of BP load between men and women. We assessed the relationship of 24-h ambulatory BP measurements and BSA in 534 participants (mean age 61 ± 3 years, 51% women) from the Helsinki Birth Cohort Study. The study subjects had no previous medication affecting vasculature or BP. When BP values were adjusted for age, smoking, physical activity, and body fat percentage, males had higher ambulatory daytime mean systolic BP (131 mmHg vs. 127 mmHg, p < 0.001), diastolic BP (83 mmHg vs. 78 mmHg, p < 0.001), and mean arterial pressure (100 mmHg vs. 96 mmHg, p < 0.001) than females. However, all BP components per unit of BSA were significantly lower in males: daytime mean systolic BP (65 mmHg vs. 71 mmHg, p < 0.001), diastolic BP (41 mmHg vs. 44 mmHg, p < 0.001), pulse pressure (24 mmHg vs. 28 mmHg, p = 0.013), and mean arterial pressure (49 mmHg vs. 54 mmHg, p < 0.001). The same phenomenon was observed in night-time BP values. BP load per BSA is higher in women than in men, which may explain many reported sex differences in cardiovascular morbidity. Relatively small-sized individuals might benefit from a more aggressive therapeutic strategy.

Body surface area and glucose tolerance - The smaller the person, the greater the 2-hour plasma glucose.

BACKGROUND: The oral glucose tolerance test (OGTT) is standardized globally with a uniform glucose load of 75 g to all adults irrespective of body size. An inverse association between body height and 2-hour postload plasma glucose (2hPG) has been demonstrated. Our aim was to evaluate the relationship between body surface area (BSA) and plasma glucose values during an OGTT. METHODS: An OGTT was performed on 2659 individuals at increased cardiovascular risk aged between 45 and 70 years of age, who had not previously been diagnosed with diabetes or cardiovascular disease. Their BSA was calculated according to the Mosteller formula. Study subjects were divided into five BSA levels corresponding to 12.5, 25, 25, 25, and 12.5% of the total distribution. FINDINGS: When adjusted for age, sex, waist circumference, alcohol intake, current smoking, and leisure-time physical activity, BSA level showed an inverse linear relationship with the 2hPG in all categories of glucose tolerance (p for linearity < 0.001). Moreover, the smaller the adjusted BSA of the study person, the higher the proportion of newly diagnosed type 2 diabetes based on 2hPG in the OGTT. INTERPRETATION: Body size has a considerable impact on the findings from a standardized OGTT. Smaller persons are more likely to be diagnosed as glucose intolerant than relatively larger sized individuals. FUNDING: This work was supported by the State Provincial Office of Western Finland, the Central Satakunta Health Federation of Municipalities, Satakunta Hospital District, and the Hospital District of Southwest Finland. RESEARCH IN CONTEXT: Evidence before this study. We searched PubMed using the MeSH terms "glucose tolerance test", "body surface area", "body height", "body size", "glucose tolerance", "insulin resistance", "blood glucose" and "diabetes mellitus" on March 10, 2019 without language restrictions. We also used Cited Reference Search in Web of Science for relevant articles. The oral glucose tolerance test (OGTT) is standardized globally with a uniform glucose load of 75 g to all adults irrespective of body size. An inverse association between body height and 2-hour postload plasma glucose (2hPG) has been demonstrated. Several studies have shown that 2hPG predicts all-cause mortality better than elevated fasting glucose. However, body height or body surface area are not usually adjusted in epidemiological studies. It is well known that short adult stature is a risk factor for cardiovascular and all-cause mortality. Added value of this study. This is the first study to assess the relationship of body surface area and 2hPG in a typical primary care population at increased cardiovascular risk. Body surface area has a considerable impact on the result of a standardized OGTT. Smaller individuals are more likely to be diagnosed as glucose intolerant than relatively larger sized individuals. Implications of all the available evidence. There is a possibility that the diagnosis of type 2 diabetes made by an OGTT is a false positive result in a relatively small individual, and a false negative result in a relatively larger individual. Association of 2hPG concentrations and mortality may be influenced by body size as confounding factor. Given that the OGTT is a time and effort consuming test both for patients and laboratory personnel, validity of the OGTT for different body sizes should be reconsidered.