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Free-Living Physical Activity Energy Expenditure Is Strongly Related to Glucose Intolerance in Cameroonian Adults Independently of Obesity
FELIX K. ASSAH
ULF EKELUND
PHD
SOREN BRAGE
PHD
JEAN CLAUDE MBANYA
PHD
NICHOLAS J. WAREHAM
PHD
C a r d i o v a s c u l a r a n d OBJECTIVE - We examined the cross-sectional association between objectively measured free-living physical activity energy expenditure (PAEE) and glucose tolerance in adult Cameroonians without known diabetes. RESEARCH DESIGN AND METHODS - PAEE was measured in 34 volunteers using the doubly labeled water method and indirect calorimetry (resting). Fasting blood glucose and 2-h postload blood glucose were measured during a standard 75-g oral glucose tolerance test. RESULTS - There was a significant negative correlation between PAEE and 2-h glucose (r 0.43; P 0.01) but not fasting glucose (r 0.1; P 0.57). The inverse association between PAEE and 2-h glucose remained after adjustment for age, sex, smoking, alcohol consumption, and BMI ( 0.017 [95% CI 0.033 to 0.002]) and was unchanged after further adjustment for waist circumference, body fat percentage, or aerobic fitness. CONCLUSIONS - PAEE is inversely associated with 2-h glucose independently of adiposity or fitness. Interventions aimed at increasing PAEE could play an important role in diabetes prevention in developing countries.
-
D a rapid epidemiologic transition
eveloping countries are undergoing
characterized by rising prevalence
of obesity, diabetes, and cardiovascular
diseases (CVDs). Recent changes in diet
and physical activity patterns have been
suggested as possible risk factors (1). It is
important to understand the association
between modifiable exposure variables
and risk factors for chronic diseases in
order to design appropriate intervention
strategies. We examined the
crosssectional association between physical
activity energy expenditure (PAEE) and
glucose tolerance in nondiabetic adult
Cameroonians.
RESEARCH DESIGN AND
METHODS A cross-sectional study
of 17 men and 17 women recruited from
an urban and a rural residential area of
Cameroon was conducted. Ethical
approval for the study was obtained from
the Cameroon National Ethics
Committee, and all participants provided signed
informed consent.
Height and waist circumference were
measured using standard clinical
procedures. Body weight was measured using
an electronic scale (Tanita TBF-531;
Tanita U.K., Middlesex, U.K.). Total body
water (TBW) was measured by deuterium
dilution. Fat-free mass was calculated
from TBW, assuming a hydration factor of
73%, and fat mass derived as the
difference between body weight and fat-free
mass.
Resting energy expenditure (REE)
was measured using the MedGem
handheld indirect calorimeter (HealtheTech
Inc., Golden, CO). Total energy
expenditure (TEE) was measured by the doubly
labeled water (DLW) method. Two
baseline urine samples were collected on
separate days before the administration of a
standard dose of DLW (174 mg/kg body
wt of oxygen-18 and 70 mg/kg body wt of
deuterium). Postdose urine samples were
collected daily for the next 6 days. TEE
was calculated using Schoellers
estimation of CO2 production, assuming a
respiratory quotient of 0.85. PAEE (kJ day1
kg 1) was calculated as 0.9 TEE
REE, taking the thermogenic effect of
food into account. Aerobic fitness was
estimated by linear extrapolation of the
individually observed heart-rate response
to a standardized step test up to the
agepredicted maximum heart rate.
Capillary blood glucose was
measured after an overnight fast (fasting
blood glucose [FBG]) and then 2 h after
ingestion of 75 g glucose dissolved in
250 300 ml water (2-h postload blood
glucose [2-h BG]). This was done using a
HemoCue B-Glucose Analyzer (HemoCue,
A ngelholm, Sweden).
Statistical analyses were done using
STATA (version 10 special edition;
StataCorp, College Station, TX). Students t
test was used to assess differences in the
descriptive variables. Independent
associations of PAEE with FBG and 2-h BG were
assessed by multiple linear regression
analyses.
RESULTS The mean SD age of
the study participants was 34.5 7.5
years. Body fat was significantly lower in
men than in women (18.5 9.3 vs.
34.6 7.2%; P 0.001); however, the
difference in BMI was of borderline
significance (25.4 3.6 vs. 28.4 5.1 kg/m2;
P 0.05).
TEE (191.4 55.9 vs. 143 22.6
kJ kg1 day1 ; P 0.002) and PAEE
(73.9 49.7 vs. 45.4 17.4 kJ kg1
day 1; P 0.03) were significantly
higher in men than in women. There was
no difference in mean FBG (4.3 0.7 vs.
4.6 0.6 mmol/l; P 0.21) or 2-h BG
(5.9 1.8 vs. 6.3 1.1 mmol/l; P
0.43) between men and women.
BMI, waist circumference, and body
fat were not significantly correlated with
FBG or 2-h BG. PAEE was not
significantly correlated with FBG (r 0.11; P
0.53) but inversely correlated with 2-h
BG (r 0.43; P 0.011).
In unadjusted linear regression
analyses (Table 1), PAEE was significantly
negatively associated with 2-h BG (
0.016 [95% CI 0.028 to 0.004]).
This association remained largely
unchanged when adjusted for age, sex,
smoking, and alcohol c (...truncated)