Pioglitazone does not modify ANP levels of type 2 diabetic patients

Background: The atrial natriuretic peptide (ANP) regulates fluid volume redistribution between heart and the pulmonary vessels. In diabetic patients the physiological action of ANP appears to be seriously altered. Methods: 12 subjects (gender 6M/6F, age 47 ± 2 years, BMI 29.1 ± 0.1 kg/m2), with type 2 diabetes and under stable conditions, were studied after one month of pioglitazione treatment (30 mg/die) by means of isotonic blood volume expansion. Results: After one month of pioglitazone treatment the meta- bolic profile of the subjects improved (decrease dia- stolic blood pressure: p = 0.05, total cholesterol: p = 0.01, triglycerides: p = 0.03 and blood glucose: p = 0.01) as the expansion of their plasma volume was found associated with the decrease of hematocrit (p < 0.05). The statistical comparison before versus after pioglitazone showed a significant decrease in the ba- sal aldosterone levels post-treatment (p < 0.04). None-theless ANP plasma levels were similar before and after therapy. Conclusions: The inappropriately high concentrations of ANP induced by hyperglycemia and the abnormal responses to a physiological sti- mulus like an isotonic blood volume expansion are not reverted by one month of pioglitazone. This is in contrast with the brisk improvement of the meta-bolic profile seen for the same period of treatment. ANP secretion is modified by fluid load in diabetic patients. This anomaly is not reverted by pioglita-zone.