The effect of oral calcium on serum level of vitamin B12 in patients with type 2 diabetes

Vitamin B12 deficiency is one of the most well-known disorders due to long-term use of metformin due to interference with its absorption.

This double-blind randomized trial was conducted from June to October 2016 at Shahid Beheshti Hospital in Qom on 60 patients in the age group of 30 to 60 years with a history of type 2 diabetes for one to two years and taking metformin in the amount of one to two grams. Patients were divided into two groups of 30 people. The intervention group received metformin with 1 gram of calcium carbonate daily, and the control group received metformin without calcium. Each of the patients in the intervention group was given 200 calcium carbonate tablets. Vitamin B12 levels of the patients in both groups were measured before the start of the intervention, and they were evaluated in terms of neuropathy according to the Michigan questionnaire. Vitamin B12 of patients and neuropathy in two groups were measured before the intervention and after three months.

There was a difference between the two groups in terms of gender, and no significant difference was observed between the mean ages in the two groups. The mean level of vitamin B12 before receiving calcium in group A (intervention) was lower than group B (control) (P=0.036) and after receiving calcium, the level of vitamin B12 in the intervention group increased (P=0.002). In the control group, the level of vitamin B12 decreased (P=0.030). (P=0.006), and in the control group there was no significant difference in the examination of neuropathy (P=0.2).

Oral calcium daily intake increases vitamin B12 levels in patients with type 2 diabetes and calcium may be able to moderate the decrease in serum vitamin B12 levels induced by metformin in patients with type 2 diabetes.