Materials and Methods: This case-control study was performed on 120 pregnant women referred to Ayatollah Rouhani hospital in Babol, private offices, and health centers to evaluate the vitamin B12 level in women with and without GDM. GDM was defined as 1) after oral ingestion of 75 g glucose, fasting plasma glucose level (PGL) >92 mg/dL, 1-hour PGL >180 mg/dL, or 2-hour PGL >153 mg/dL during 24-28 weeks of gestational age, or 2) in the 100-g oral glucose tolerance test (OGTT), PGL >195 mg/dL, one-hour PGL >180 mg/dL, 2-hour PGL >155, and 3-hour PGL >140, and GDM was diagnosed if there were at least 2 out of 4 mentioned cases. According to the above definition, pregnant women with GDM were placed in the case group, while those without GDM were placed in the control group. After 8 hours of fasting, intravenous blood samples were taken and sent to the laboratory for measurement, and vitamin B12 deficiency was considered <99 pg/dL after 28 gestational weeks.

Results: Vitamin B12 deficiency was prevalent in 14.2% of 120 pregnant women studied. Vitamin B12 deficiency was more common in GDM women than in non-GDM women (58.8%-41.2%). A normal level of vitamin B12 could act as a protective factor against GDM. The vitamin B12 levels increased in the 30- to 40-year-old women with GDM. In other age groups, vitamin B12 levels were higher in non-GDM women than in GDM women. Among 17 women with vitamin B12 deficiency, 52.9% had a fasting PGL >92.

Conclusions: The results of the present study suggest that measuring vitamin B12 levels may aid in the early diagnosis of GDM and prevent maternal and fetal complications.