Relationship between obesity and maximal insulin-stimulated glucose uptake in vivo and in vitro in Pima Indians.
Previous studies have left unanswered whether human obesity, independent of glucose intolerance, is associated with a "postreceptor" defect in insulin action. We have studied the relationship between the degree of obesity (as estimated by underwater weighing) and the maximal insulin-stimulated glucose disposal rate (M) in vivo in 52 glucose-tolerant Pima Indian males. The relationship was examined independently of differences in age and maximal oxygen uptake (an estimate of "physical fitness"). The maximal insulin-stimulated glucose transport rate (MTR) was also measured in isolated abdominal adipocytes from the same subjects to determine whether differences in M could be explained by differences in glucose transport. The results showed that there was a large variance in M and MTR among these glucose-tolerant subjects. M was better correlated with glucose storage rates than with oxidation rates, as estimated by indirect calorimetry. The most obese subjects had only a 20% lower mean M and 30% lower MTR than the most lean subjects. The lower M in the obese subjects was due to both lower glucose oxidation and storage rates. There was no significant, independent correlation between age or degree of obesity and M or MTR. The maximal oxygen uptake (VO2 max) appeared to independently account for 20% of the variance observed in M. MTR was only weakly correlated with M (r = 0.36, P less than 0.02). We concluded that differences in M in these glucose-tolerant subjects must be explained by factor(s) other than maximal oxygen uptake, age, maximal insulin-stimulated glucose transport in vitro, or degree of adiposity per se.
D000273:Adipose Tissue / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000375:Aging; D001130:Arizona; D001692:Biological Transport; D001786:Blood Glucose / Q000378:metabolism*; D001823:Body Composition; D002153:Calorimetry, Indirect; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007198:Indians, North American; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009765:Obesity / Q000378:metabolism*; D010101:Oxygen Consumption
D001786:Blood Glucose; D007328:Insulin; D005947:Glucose