Subcutaneous adipose tissue expression of tumour necrosis factor-alpha is not associated with whole body insulin resistance in obese nondiabetic or in type-2 diabetic subjects

Background An association with subcutaneous adipose tissue TNF alpha expres sion and insulin resistance has been suggested in obesity/type-2 diabetes, but this has not been examined directly. In the first part of the study we investigated whether this association is present in 7 lean, 10 obese nondia betic and 9 type-2 diabetic men. In the second part of the study we examine d the relationship between adipose tissue TNF alpha mRNA levels and BMI in 81 nondiabetic subjects spanning a wide range of BMIs. Methods Subcutaneous adipose tissue TNF alpha mRNA levels and insulin sensi tivity were determined with quantitative RT-competitive PCR and hyperinsuli naemic clamp, respectively. Results Subcutaneous adipose tissue TNF alpha mRNA levels were similar in 7 lean and 10 obese nondiabetic and 9 type-2 diabetic men (P = 0.68), and di d not change in response to 240-min hyperinsulinaemia. TNF alpha mRNA level s and insulin sensitivity were not correlated. Unexpectedly, no correlation between TNF alpha mRNA and BMI was found. The relationship between adipose tissue TNF alpha mRNA and BMI was examined further in 31 male and 50 femal e nondiabetic subjects. The subcutaneous adipose tissue TNF alpha mRNA leve l correlated with BMI in all subjects (r(S) = 0.32, P < 0.01), and in a sub group analysis in men (r(S) = 0.55, P < 0.01) but not in women (r(S) = - 0. 08). The correlation in men was dependent on a fourfold higher TNF alpha mR NA level in 5 morbidly obese men while there was no difference in TNF alpha mRNA levels in lean or obese men. Conclusions Subcutaneous adipose tissue TNF alpha expression does not corre late with insulin sensitivity in nondiabetic or type-2 diabetic men; is not regulated by acute hyperinsulinaemia; and is increased only in morbidly ob ese men.