Assessment of vitamin B12 levels and cardiovascular risk factors in metformin- and non-metformin-treated type 2 diabetic patients

Oxidative stress enhances cardiovascular risk. Metformin decreases intestinal absorption of vitamin B12. Our objective was the evaluation of type 2 diabetics focusing on differences due to their treatment. A prospective study on 224 type 2 diabetics was realized between 2015-2018 in Targu Mures, Romania, divided into 2 subgroups (metformin vs. other therapy - 2nd/3rd generation sulfonylureas, insulin, dietary regimen-, followed for at least one year) and non -diabetic controls (n=25) for oxidative stress level comparison. Serum homocysteine (HC), vitamin B12 were determined by chemiluminescence (Immulite One). Lipid peroxidation was assessed by serum malondialdehyde (MDA) measurement (HPLC). Biochemical tests, minerals, cystatin C, high-sensitivity C reactive protein (hs-CRP) were measured on Konelab20Xti, glycated hemoglobin on Nycocard Reader. GraphPad InStat-3 was used for statistics. Negative correlation occured between serum vitamin B12 and HC, this vitamin's level was significantly lower and serum zinc was significantly higher in patients on metformin. Hyperhomocysteinemia was present in 87% of the subjects, 46% had zinc deficiency and 41% elevated hs-CRP. Serum cystatin C showed positive correlation with creatinine. Serum MDA was significantly higher in diabetics compared to control patients. Elevated hs-CRP and homocysteine represent raised cardiovascular risk. Intense oxidative stress, vitamin, mineral deficiencies are frequent in diabetic subjects.