Use of the oral hypoglycemic rosiglitazone (Avandia® | GlaxoSmithKline) may help to slow down the progression of diabetic retinopathy, according to a study by researcher Shen LQ, et al., published in the latest June 2008 issue of the Archives of Ophthalmology.
The study was conducted on 124 patients treated with rosiglitazone, receiving eye care at the Joslin Diabetes Center in Boston, during the period May 2002 and May 2003. Appropriately matched controls (n=158) who were not on rosiglitazone were arranged. It was observed that the eyes with severe nonproliferative diabetic retinopathy progressed to progressive diabetic retinopathy in only 19.2% of the rosiglitazone-treated patients, compared to 47.4% of the control group. Thus, there was a 59% relative risk reduction when rosiglitazone was used. Also, there were fewer patients from the rosiglitazone group experiencing 3 or more lines of visual acuity loss (P=0.03).
In another study conducted recently, (Diabetes and Vascular Disease Research, June 2008), 16 diabetic men with hypogonadism were evaluated before and after 8mg/day rosiglitazone treatment. The study concluded that the study concluded that the hypoglycemic rosiglitazone increased the levels of bioavailable, free and total testosterone and sex hormone binding globulin in hypogondal men with type 2 diabetes.. A French study by Ratziu V, et al. (Gastroenterology, April 2008) examined the effect of rosiglitazone treatment in 63 patients with histologically proven nonalcoholic steatohepatitis (NASH) and deduced that the drug can significantly improve steatosis and transaminase levels.
Glitazones increase insulin sensitivity by selective agonism of peroxisome proliferator activated receptors (PPAR-gamma) which are present in muscle, liver and adipose tissue. They reduce blood glucose, as well as glycosylated hemoglobin levels. Glitazones are a unique class of drugs, being the only class of oral antidiabetics which augment tissue insulin sensitivity. However, their use as monotherapy is generally not favored. The most potent glitazone is rosiglitazone followed by pioglitazone. Recently, there have been negative reports on rosiglitazone which has been found to be associated with a higher cardiovascular risk (New England Journal of Medicine, 2007).
Diabetic retinopathy is the leading cause of new onset blindness in the age group 25-74 years in the United States. The disease progresses from increased vascular permeability (nonproliferative) to retinal and vitreal angiogenesis (proliferative). Several findings may be evident on fundoscopy, including microaneurysms, dot and blot hemorrhages, flame shaped hemorrhages and cotton wool spots. The patient is initially asymptomatic, but may gradually develop blurring of vision and vision loss. Laser photocoagulation has been used with success to treat this condition. However, strict glycemic control and regular follow up are vital in preventing as well as managing this disabling disease.
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References
1. Shen LQ, Child A, Weber GM, Folkman J, Aiello LP. Rosiglitazone and Delayed Onset of Proliferative Diabetic Retinopathy. Arch Ophthalmol. 2008 Jun;126(6):793-9.
2. Kapoor D, Channer KS, Jones TH. Rosiglitazone increases bioactive testosterone and reduces waist circumference in hypogonadal men with type 2 diabetes. Diab Vasc Dis Res. 2008 Jun;5(2):135-7.
3. Ratziu V, Giral P, Jacqueminet S, et al. Rosiglitazone for Nonalcoholic Steatohepatitis: One-Year Results of the Randomized Placebo-Controlled Fatty Liver Improvement With Rosiglitazone Therapy (FLIRT) Trial. Gastroenterology. 2008 Apr 8. [Epub ahead of print].
4. Nissen SE, Wolski K. Effect of rosiglitazone on the risk of myocardial infarction and death from cardiovascular causes. N Engl J Med. 2007 Jun 14;356(24):2457-71. Epub 2007 May 21.
5. Fong DS, Aiello L, Gardner TW, et al. Diabetic retinopathy. Diabetes Care. 2003 Jan;26 (Suppl 1):S99-S102.
