Background: Pioglitazone shows potential for improving insulin dynamics in horses but longer-term clinical evaluation is necessary.Hypothesis/
Objectives: To characterize the effects of 2 doses of pioglitazone on insulin dynamics in equids with severe insulin dysregulation (ID) over an extended study period. Animals: 17 client-owned equids with severe ID (resting insulin >100 µIU/mL)
Methods: Prospective cohort study. Equids received 2mg/kg pioglitazone orally either sid (PIO-SID) or bid (PIO-BID). Eight resting blood samples over a 70 day study period were analyzed for insulin, high molecular weight adiponectin and pioglitazone concentration. Oral sugar tests (OST) were performed on days 0 and 28. Data were analyzed using linear regression and t-tests.
Results: Basal serum insulin did not change significantly over time for PIO-SID (p=0.49) or PIO-BID (p=0.36). Mean [95% CI] post OST insulin (µIU/mL) did not change significantly (day 0 vs 28) for PIO-SID (249 [74-424] vs 517 [38-997]; P=0.4) or PIO-BID (265 [157-372] vs 165 [34-297] P=0.2). Adiponectin (day 0 vs 70, μg/mL) increased in PIO-SID (0.7 [0.2-1.3] vs 4 [-3-11.1]; P=0.01) and PIO-BID (3.5 [-.3-7.2] vs 15 [6.9-23]; Conclusions and clinical importance: Pioglitazone did not significantly improve insulin dynamics; however, there was a marked increase in adiponectin particularly with twice daily administration: a potentially beneficial effect independent of insulin control. Plasma pioglitazone concentrations only reached the low end of the human therapeutic range with twice daily administration.
