The glucoregulatory and antilipolytic actions of insulin in abdominal obesity with normal or impaired glucose tolerance: an in vivo and in vitro study.
To evaluate the effects of obesity and impaired glucose tolerance on insulin sensitivity, we performed a euglycaemic-hyperinsulinemic clamp at about 350 pmol l-1, combined with 3H-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 mumol m-2 min-1, P < 0.001). Plasma glycerol was higher in oIGT than in oNGT and in the controls, both fasting (238 +/- 12 vs. 179 +/- 14 vs. 112 +/- 8 mumol l-1, P < 0.001) and during the clamp (175 +/- 21 vs. 120 +/- 12 vs. 36 +/- 6 mumol l-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 = 0.036; 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).(ABSTRACT TRUNCATED AT 250 WORDS)
Cavallo-Perin
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P
Institute of Internal Medicine, University of Turin, Italy.
Bruno
A
A
Cassader
M
M
Cesco
L
L
Gruden
G
G
Pagano
G
G
D000005:Abdomen; D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D005990:Glycerol / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D007333:Insulin Resistance; D008066:Lipolysis / Q000187:drug effects; D008099:Liver / Q000378:metabolism; D008297:Male; D009765:Obesity / Q000378:metabolism*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005947:Glucose; D005990:Glycerol