Objective: Recently we have demonstrated that treatment with niacin raises adiponectin between 52% and 95% in patients with the metabolic syndrome. In this study we investigated whether all three adiponectin fractions are increased equally, and, secondly, whether the increase in the biologically most active high-molecular weight (HMW) fraction can prevent the deterioration of insulin sensitivity that was also observed after niacin.
Methods and results: We used sera frozen at -80 degrees C from a randomized double-blind placebo-controlled treatment study in which 20 men with the metabolic syndrome received 1500 mg niacin for 6 weeks. Low- and medium-molecular weight adiponectin increased by 35% and 33%, respectively, but HMW adiponectin by 88% (all p<0.05). The increase in HMW adiponectin was almost two times as large in patients with lower BMI and better insulin sensitivity. However, treatment with niacin induced a deterioration of insulin sensitivity, as assessed by the HOMA-IR, independently of the increase in HMW adiponectin.
Conclusion: HMW adiponectin is the fraction most affected by treatment with niacin. The niacin-associated deterioration of insulin sensitivity, however, occurs even in subgroups with the greatest increase of HMW adiponectin.