[Relationship between peripheral insulin resistance and beta-cell function in obese subjects].
OBJECTIVE
To detect the relationship between peripheral insulin resistance and beta-cell function in obese subjects with normal blood glucose, and to explore the role of free fatty acids (FFAs) in the pathogenesis of type 2 DM.


METHODS
Ten simple obesity male subjects (OB) with normal blood glucose and 10 lean male persons (NC) matched on age and living style were included. None of them was smoker, and their blood pressure, serum cholesterol levels were all normal. All subjects underwent the following tests: (1) Fasting serum lipids profile and FFA; (2) Baseline immunoreactive insulin (IRI), pro-insulin (PI) and true-insulin (TI); (3) Acute insulin response (AIR) to an intravenous bonus of glucose; (4) Euglycemic hyperinsulinemia clamp study to assess the peripheral glucose disposal rate (GDR).


RESULTS
In obesity subjects, the baseline IRI, PI and TI were elevated and the ratio of PI/(PI + TI) was higher than controls (P < 0.01). The AIR was enhanced in OB and the area under the curve was larger (P < 0.05), but in obesity subjects the plasma glucose levels at 3, 5 and 10 minutes were much higher than controls (P < 0.05). The GDRs obtained during steady state were markedly decreased in OB (P < 0.05). The serum lipids profiles were normal except that triglyceride was higher in OB (P < 0.05) and the FFAs concentration was also elevated in OB (P < 0.05). There was a negative correlation between FFAs concentration and GDR in OB groups (r = -0.767, P < 0.01).


CONCLUSIONS
The present data showed that in obese subjects with normal blood glucose, there were severe peripheral insulin resistance, relative deficiency of beta-cell first-phase insulin release and increased ratio of pro-insulin to insulin. It is logical to deduce that both insulin resistance and the beta-cell changes could be, at least partially, secondary to high levels of serum FFAs. Elevated circulating FFAs may paly a role in the pathogenesis of type 2 DM.
Li
Hong-liang
HL
Department of Endocrinology, West China Hospital, Sichuan University, Chengdu 610041, China.
Yu
Ye-rong
YR
Yu
Hong-ling
HL
Wang
Chun
C
Zhang
Xiang-xun
XX
D000328:Adult; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D007333:Insulin Resistance; D050417:Insulin-Secreting Cells / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*
D005230:Fatty Acids, Nonesterified