The effects of metformin and pioglitazone on ghrelin, a physiologic regulator of appetite and food intake, have not been clearly established. In a randomized clinical trial, we randomly assigned 60 type 2 diabetic patients to either metformin (Group A; n = 30) or pioglitazone (Group B; n = 30) treatment groups. The groups were similar in their baseline characteristics. A standard fasting 75 g oral glucose tolerance test was performed at time zero before starting metformin or pioglitazone, and 3 months later. After 3 months of treatment, pioglitazone, but not metformin, was significantly associated with weight gain. Both groups experienced a significant reduction in fasting plasma glucose (p < 0.01), hemoglobin A1c (p < 0.01 in Group A and p < 0.05 in Group B), and insulin resistance (p < 0.01). The effect of metformin on preprandial ghrelin and its response to glucose challenge was not significant, while the pioglitazone group had a significant reduction in preprandial ghrelin levels after treatment (p < 0.05). The effect of pioglitazone on ghrelin was independent of changes in body weight, body mass index, glucose control, insulin resistance, and plasma insulin. In conclusion, treatment with pioglitazone is associated with a decrease in preprandial ghrelin levels and therefore, the weight gain and increased food intake related to pioglitazone use cannot be explained by its effects on ghrelin. The effect of pioglitazone on ghrelin is independent of changes in body weight, body mass index, plasma insulin, insulin resistance, or glucose control.
- Glucose tolerance