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.