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 - 2^nd/3^rd 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.