OBJECTIVE The aim was to study the association of the use of an oral antihyperglycemic agent metformin with the presence of ocular complications in patients with type 2 diabetes (T2D). METHODS Medical records were reviewed for 234 patients with diagnosed T2D. 81.2% (n=190) patients were using metformin and 18.8% (n=44) using other oral antihyperglycemic agents. Plasma glucose concentration, glycated haemoglobin, and the presence of ocular complications in patients treated with metformin were compared to those in patients treated with other oral antihyperglycemic agents. RESULTS Ocular complications occurred in 65 patients (27.8%). Patients treated with metformin had fewer ocular complications compared to patients treated with other oral antihyperglycemic agents (χ2=19.985; p<0.0001). After adjustment for gender, age, duration of T2D, serum concentration of cholesterol, smoking, body mass index and presence of other diseases, treatment with metformin decreased the odds of both glaucoma (OR=0.14, 95% CI: 0.03-0.57, p=0.006) and diabetic retinopathy (OR=0.33, 95% CI: 0.14-0.82, p=0.017) compared with other oral antihyperglycemic agents. CONCLUSION Our results suggest that metformin may have a protective effect on ocular complications, especially glaucoma, in patients with T2D. The effects of metformin either regarding prevention of ocular complications or ocular complications already developed in patients with T2D, should be further investigated.

Aim In order to increase the database related to the antineoplastic potential of metformin, association between the use of metformin and risk of cancer occurence in patients with diabetes mellitus type 2 (DM2) was investigated. Methods In this cross-sectional study, medical records of patients with DM2 were reviewed for cancer occurence. Data on age, body mass index (BMI), alcohol and nicotine consumption, glucose and HbA1c levels, duration of DM2, medication used in the treatment of DM2 and cancer occurence were collected and analyzed. Unpaired Student's t-test or Mann-Whitney U test were used for comparisons between treatment groups, and logistic regression to asses how well our set of predictor variables predicts occurence of carcinoma. P-value less than 0.05 was considered statistically significant. Results The mean age of 234 included patients was 66.8±11.5 years, and DM2 duration was 7± 6.49 years. Mean glucose value was 8.51±4.17mmol/L, and HbA1c 7.74±1.53. Metformin therapy was prescribed in 190 (81%) patients. Cancer was diagnosed in 16 (6.8%) patients: prostate cancer in eight (3.4%), breast cancer in four (1.7%), rectal cancer in two (0.9%) and cancer of the uterus and cervix in one patient. Age, duration of DM2 and BMI did not contribute significantly to the model, while metformin use was shown to be a significant independent predictor (OR=0.049; 95% CI=0.013-0.181; p=0.001). Conclusion Our findings support the hypothesis that the use of metformin compared to the use of other oral antidiabetic drugs is associated with a lower risk of cancer in patients with DM2.