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

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Abstract
An association with subcutaneous adipose tissue TNFα expression 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 nondiabetic and 9 type-2 diabetic men. In the second part of the study we examined the relationship between adipose tissue TNFα mRNA levels and BMI in 81 nondiabetic subjects spanning a wide range of BMIs. Subcutaneous adipose tissue TNFα mRNA levels and insulin sensitivity were determined with quantitative RT-competitive PCR and hyperinsulinaemic clamp, respectively. Subcutaneous adipose tissue TNFα mRNA levels were similar in 7 lean and 10 obese nondiabetic and 9 type-2 diabetic men (P = 0.68), and did not change in response to 240-min hyperinsulinaemia. TNFα mRNA levels and insulin sensitivity were not correlated. Unexpectedly, no correlation between TNFα mRNA and BMI was found. The relationship between adipose tissue TNFα mRNA and BMI was examined further in 31 male and 50 female nondiabetic subjects. The subcutaneous adipose tissue TNFα mRNA level correlated with BMI in all subjects (rS = 0.32, P < 0.01), and in a subgroup analysis in men (rS = 0.55, P < 0.01) but not in women (rS = − 0.08). The correlation in men was dependent on a fourfold higher TNFα mRNA level in 5 morbidly obese men while there was no difference in TNFα mRNA levels in lean or obese men. Subcutaneous adipose tissue TNFα expression does not correlate with insulin sensitivity in nondiabetic or type-2 diabetic men; is not regulated by acute hyperinsulinaemia; and is increased only in morbidly obese men.