Diabetic macular edema: correlations with available diabetes therapies--evidence across a qualitative review of published literature from MEDLINE and EMBASE.

Diabetic macular edema (DME) is the leading cause of visual loss and legal blindness in people with diabetes mellitus. The pathogenesis of DME is complex and multifactorial, and involves both local and systemic risk factors that may alter the blood-retina barrier and allow leakage of protein and fluid into the macula. Recently, in addition to well known risk factors, the use of thiazolidinediones (glitazones) has been related to the development and worsening of DME. This review is based on available literature derived from EMBASE and MEDLINE, from 1950 to May 2010, and focuses on the potential correlations between DME and current available therapies for type 1 and 2 diabetes. This review reveals that the current literature, with the potential exception of glitazones, is not sufficient for a definite statement on the association between DME and currently available diabetic therapies. In fact, among antidiabetic agents, the class of glitazones appears the only one to be potentially associated with DME. Furthermore, adequately powered, prospective studies are warranted to evaluate the exact causal association between glitazones and DME and to exclude the role of other confounding factors potentially able to induce or exacerbate macular edema. Improvement of the quality and reporting in postmarketing surveillance and the use of the 'dechallenge and rechallenge' approach in case of suspicious cause/effect drug relationship of DME are highly encouraged.