Effect of Pioglitazone Therapy for Type 2 Diabetes on Vision

To evaluate the safety of pioglitazone treatment for diabetes. Recent reports suggest that oral glitazone treatment may cause or exacerbate retinal edema. We hypothesized that glitazone treatment may cause subclinical edema evidenced by increased retinal thickness. We will conduct a double-masked, prospective safety study of 19 subjects undergoing placebo-controlled treatment with pioglitazone. Patient treatment consisted of either insulin with placebo or insulin with pioglitazone. The main outcome measures are ETDRS visual acuity and retinal thickness measured with optical coherence tomography.

Inclusion criteria

• Male or female patients with type 2 diabetes mellitus on insulin therapy, 30-75 years of age with Hgb 1c values between 7.5 - 10% and a BMI of < 40kg/m2.
• Patients were enrolled if they have been on a stable anti-hypertensive and lipid regimen for 90 days prior to study randomization.
• Patients must have had the ability to understand the requirements of the study, provide written consent and agree to abide by study requirements.

Exclusion criteria

• Prior treatment with sulfonylurea, or metformin within 21 days before study entry, prior treatment with NSAIDs, or diuretics within 21 days of screening, serum creatinine levels above 1.5 mg/dl for males or above 1.4 for females or creatinine clearance less than 70 ml/min by Cockcroft and Gault, or serum albumin levels of less than 2.5 gm/dl.
• Other exclusion criteria were elevated hepatic enzymes (aspartate aminotransferase or alanine aminotransferase more than 2.5 times upper limit of normal) or uncontrolled or untreated significant pulmonary, neurological condition, or cardiovascular disease, including hypertension, congestive heart failure (specifically New York Heart Association Type III or IV patients), angina, peripheral vascular disease, or greater than +1 peripheral edema.
• Furthermore, any patients with any condition that would jeopardize their safety or affect the validity of the trial results were excluded from this study.