Objective To determine the effect of retrobular injection of triamcinolone acetonide on blood glucose in the elderly patients with diabetic and non-diabetic macular edema (ME). Methods A total of 80 elderly patients (over 65 years old)with diabetic and non-diabetic ME admitted in Ophthalmological Department of our hospital from December 2015 to November 2016 were enrolled in this study. They were divided into diabetic and non-diabetic groups, with 40 cases(40 eyes) in each group, and underwent retrobulbar injection of 20 mg triamcinolone acetonide.Fasting plasma glucose(FPG) and 2-hour postprandial blood glucose (2hPBG) were mea-sured on the day of treatment (before treatment), on continuous 7 days and in 14 d(2 weeks) after treatment. SPSS statistics 17.0 was used to perform the statistical analysis. Analysis of variance was employed for the intra-group comparison, and independent sample t test for comparison between groups. Results The FPG [(5.35±0.33)mmol/L] and 2hPBG [(7.66±0.34)mmol/L] levels reached the highest values on day 2 in the non-diabetic group, but for the diabetic group, the peak values were observed on day 2 [(8.53±0.59)mmol/L]and day 3 [(13.32±2.70)mmol/L]respectively, with statistical significances in the time points. There were no differences in blood glucose level in the non-diabetic group on days 4,5,6,7 and 14 with that before treatment. But, the level was obviously increased in the diabetic group even on day 14 when compared with that before treatment. What’s more, the maximum difference of FPG [(0.65±0.21) vs (2.91±0.27)mmol/L] and 2hPGB [(1.10±0.37) vs (4.59±2.15)mmol/L] were more significantly increased in the diabetic group than in the non-diabetic group (P<0.01). Conclusion Retrobular injection of triamcinolone acetonide results in increased blood glucose, with the peak on day 2 or 3 after injection, and the effect is more significant for diabetic patients. Ophthalmologists should pay great attention on systemic side effects of such drugs.