Results:

Plasma IL-1β was near detection limit (0.071–0.216 pg ml− 1), while IL-1Ra accumulated at 1000-folds higher (77–1068 pg ml− 1). Plasma apoB (0.34–1.80 g l− 1) associated significantly with hypersinsulinemia (total IVGTT: C-peptide r= 0.27, insulin r= 0.22), IR (M/I=− 0.29) and plasma IL-1Ra (r= 0.26) but not with IL-1β. Plasma IL-1Ra associated with plasma IL-1β (r= 0.40), and more strongly with hyperinsulinemia and IR than apoB, while the association of plasma IL-1β was limited to second phase and total insulin secretion (r= 0.23). Adjusting the association of plasma apoB to hyperinsulinemia and IR for IL-1Ra eliminated these associations. Furthermore, despite equivalent body composition, subjects with hyperapoB (⩾ 80th percentile, 1.14 g l− 1) had higher C-peptide secretion and lower insulin sensitivity than those with low plasma apoB (⩽ 20th percentile, 0.78 g l− 1). Adjustment for plasma IL-1 Ra eliminated all group differences.

Conclusion:

Plasma apoB is associated with hyperinsulinemia and IR in normoglycemic obese subjects, which is eliminated upon adjustment for plasma IL-1Ra. This may implicate the IL-1 family in elevated risks for T2D in obese subjects with hyperapoB.