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The glucoregulatory and antilipolytic actions of insulin in abdominal obesity with normal or impaired glucose tolerance: an in vivo and in vitro study
Author(s) -
CAVALLOPERIN P.,
BRUNO A.,
CASSADER M.,
CESCO L.,
GRUDEN G.,
PAGANO G.
Publication year - 1992
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1992.tb01436.x
Subject(s) - medicine , endocrinology , lipolysis , impaired glucose tolerance , insulin , glucose clamp technique , insulin resistance , obesity , clamp , glucose uptake , glucose tolerance test , in vivo , adipose tissue , pancreatic hormone , biology , mechanical engineering , clamping , engineering , microbiology and biotechnology
. To evaluate the effects of obesity and impaired glucose tolerance on insulin sensitivity, we performed a euglycaemic‐hyperinsulinemic clamp at about 350 pmol 1 ‐1 , combined with 3 H‐glucose infusion, in 14 obese patients, BMI 36.5 ± 1.2 and in 12 matched controls, BMI 23.9 ± 0.4. Six obese patients had normal glucose tolerance (oNGT), and eight had impaired glucose tolerance (oIGT). The ability of insulin to inhibit lipolysis in isolated adipocytes was also studied. Insulin‐mediated glucose utilization was more severely impaired in oIGT than in oNGT with respect to the controls (621 ± 51 vs. 897 ±83 vs. 1298 ± 55 μmol m ‐2 min ‐1 , P<0.001). Plasma gly‐cerol was higher in oIGT than in oNGT and in the controls, both fasting (238 ±12 vs. 179 ± 14 vs. 112 ± 8 μmo1 1 ‐1 , P < 0.001) and during the clamp (175 ± 21 vs. 120 ± 12 vs. 36 ± 6/μmiol1 ‐1 , P<0.001). The correlation between glucose utilization and the percent reduction of plasma glycerol during the clamp was significant in the study group as a whole (r = 0.809, P=0.0001), and in each of the groups separately (oIGT: r = 0.929, P = 0.002; oNGT: r = 0.943, P = 0036; controls: r = 0.902, P = 0.0001). Inhibition by insulin of noradrenaline‐stimulated lipolysis in isolated adipocytes was more severely impaired in oIGT than in oNGT compared with the controls (P < 0.001). We conclude that impaired as opposed to normal glucose tolerance in obesity is associated with more severe impairment in both glucose utilization and insulin inhibition of lipolysis.