Abstract
Purpose: :
Thiazolidinediones (TZDs) are a class of oral pharmacological agents known as insulin sensitizers used to treat Diabetes Mellitus Type 2 (DM2). There has been speculation that fluid retention associated with TZD use leads to worsening diabetic macular edema with improvement or resolution of this edema with drug cessation. The purpose of this study was to determine the prevalence of clinically significant macular edema (CSME) in patients on pioglitazone (TZD on formulary at Parkland Health & Hospital System) and whether or not there was an association between CSME and pioglitazone use. This group was compared with patients on metformin.
Methods: :
A retrospective chart review was performed on patients with DM2 seen in the Parkland Ophthalmology Clinic between 01 January 2005 and 31 December 2005 on monotherapy with either pioglitazone or metformin who filled their prescriptions at Parkland Health & Hospital System and had a HgA1C result within 6 months of the date of clinic visit. Patients with poor adherence to medications (defined as a fill rate of prescriptions <85%) were excluded. Data collected included age, sex, race, type of diabetic retinopathy if present, presence or absence of CSME, and HgA1C. The primary outcome of the study was whether or not there was an increased prevalence of CSME in patients taking thiazolidinediones compared with metformin. Approval was obtained from the Institutional Review Boards at the University of Texas Southwestern Medical Center and Parkland Health & Hospital System.
Results: :
Fourteen hundred and ninety-one charts were reviewed. One hundred and one patients met inclusion criteria for this study. There were 23 patients (46 eyes) in the pioglitazone group. Eighteen of these eyes (39.1%) had evidence of some type of diabetic retinopathy. Three eyes (6.5%) had CSME. The average HgA1C was 8.27%. There were 78 patients (156 eyes) in the metformin group. Thirty-two of these eyes (20.5%) had evidence of some type of diabetic retinopathy. Four eyes (2.6%) had CSME. The average HgA1C was 7.18%. There was no statistically significant difference with regards to age or race between the two groups, nor was there a statistically significant difference in the prevalence of CSME.
Conclusions: :
This is the first study to investigate patients solely on a TZD for DM2 in association with diabetic macular edema. While patients in the pioglitazone group had a higher HgA1C and more evidence of diabetic retinopathy, there was no increased prevalence of CSME in patients on pioglitazone monotherapy when compared with patients on metformin monotherapy.
Keywords: diabetes • macula/fovea • edema