DIABETES AND AMD

Diabetic patients do not appear to be at any increased risk of developing age-related macular degeneration (AMD) compared to the general population, according to findings from the Tromso Eye Study, reported by Maja Gran Erke MD at the 22nd Meeting of the European Association for the Study of Diabetes’ Eye Complications Study Group. “In the Tromso Eye Study, we did not observe any statistically significant association between diabetes mellitus and AMD. This is consistent with results from other cross-sectional population-based studies,†said Dr Erke, University Hospital of North Norway, and Tromso Norway.

She noted that the Tromso Eye Study is a sub-study of the multipurpose Tromso Study conducted in 2007-2008 in the municipality of Tromso, Norway. The Tromso studies were initiated in 1974 in an attempt to help combat the high mortality due to cardiovascular diseases in Norway and were gradually expanded to include many other diseases, she said. In their study of the association between diabetes mellitus and AMD, the Tromso Eye Study investigators included 2,605 Caucasians aged 65 to 87 years with gradable digital retinal photographs and available data on their diabetes status.

The Tromso Eye Study team graded the retinal photographs based on the international classification system for AMD, Dr Erke said. They defined the predominant phenotype as that of the more severe lesion present in either eye. They defined diabetes mellitus as nonfasting blood glucose of 11.1 mmol/L or more, an HbA1c greater than 6.5 per cent, or the current use of anti-diabetic medication. The researchers could find no statistically significant relationships between diabetes and AMD, in univariate or multivariate analyses. Geographic atrophy or neovascular AMD was present in 12 (4.8 per cent) of 249 diabetic individuals and 80 (3.4 per cent) of 2,356 of those without diabetes. Dr Erke noted that the absence of a significant association between diabetes and AMD persisted after adjustment for potential confounders, such as age, sex, smoking status, alcohol consumption, education, body mass index, waist-to-hip ratio, blood pressure, physical activity, blood lipids.

For example, the age- and sex-adjusted odds ratios were 0.92 (95 per cent CI 0.68- 1.25) for intermediate drusen 63.0 μm to 125.0 μm in size, 0.8 (95 per cent CI 0.56- 1.14) for large drusen greater than 125.0 μm in size, 1.92 (95 per cent CI 0.70-5.28) for geographic atrophy, and 0.93 for neovascular AMD (95 per cent CI 0.41-2.13). On the other hand, the researchers found that diabetic individuals were significantly more likely to abstain from alcohol, have an inactive lifestyle, to have higher body mass index, waist-to-hip ratio, and serum blood lipids than non-diabetic individual (p ≤ 0.001 in all cases).

Dr Erke noted that Tromso Eye Study’s findings are at variance with findings of some other studies. For example, the EUREYE study, which involved participants from seven European countries, and the Blue Mountains Eye Study from Australia both showed an association between diabetes and AMD. She also pointed out that there may have been potential confounders in the Tromso Eye Study, which might include mis-classification of AMD status and diabetes status.