Abstract

Background: Liver fat is an important determinant of insulin requirements during insulin therapy. Peroxisome proliferator-activated receptor (PPAR)-γ agonists reduce liver fat. We therefore hypothesized that type 2 diabetic patients using exceptionally high doses of insulin might respond well to addition of a PPARγ agonist.

Methods: We determined the effect of the PPARγ agonist rosiglitazone on liver fat and directly measured hepatic insulin sensitivity in 14 patients with type 2 diabetes (aged 51 ± 3 yr, body mass index 36.7 ± 1.1 kg/m2), who were poorly controlled (glycosylated hemoglobin A1c (HbA1c) 8.9 ± 0.4%) despite using high doses of insulin (218 ± 22 IU/d) in combination with metformin. Liver fat content (1H-magnetic resonance spectroscopy), hepatic insulin sensitivity [6 h hyperinsulinemic euglycemic clamp (insulin 0.3 mU/kg·min) combined with [3-3H]glucose], body composition (magnetic resonance imaging), substrate oxidation rates (indirect calorimetry), clinical parameters, and liver enzymes were measured before and after rosiglitazone treatment (8 mg/d) for 8 months.

Results: During rosiglitazone, HbA1c decreased from 8.9 ± 0.4% to 7.8 ± 0.3% (P = 0.007) and insulin requirements from 218 ± 22 to 129 ± 20 IU/d (P = 0.002). Liver fat content decreased by 46 ± 9% from 20 ± 3% to 11 ± 3% (P = 0.0002). Hepatic insulin sensitivity, measured from the percent suppression of endogenous glucose production by insulin, increased from −40 ± 7% to −89 ± 12% (P = 0.001). The percent change in liver fat correlated with the percent decrease in HbA1c (r = 0.53, P = 0.06), insulin dose (r = 0.66, P = 0.014), and suppression of endogenous glucose production (r = 0.76, P = 0.003).

Conclusions: Our results suggest that rosiglitazone may be particularly effective in type 2 diabetic patients who are poorly controlled despite using high insulin doses. The mechanism is likely to involve reduced liver fat and enhanced hepatic insulin sensitivity.

You do not currently have access to this article.