Abstract
Vitamin B12, also known as cobalamin, is a water-soluble vitamin. It is essential for the formation of red blood cells (RBCs), synthesis of genetic material- deoxyribonucleic acid (DNA), and development and function of healthy nerve cells. The deficiency of vitamin B12 can increase the risk of anemia, celiac disease, nephropathy, and immune system disorders. A recent study has reported that diabetic patients using metformin in their treatment are more prone to vitamin B12 deficiency.
What Is Diabetes Mellitus?
Diabetes Mellitus is a chronic disease caused due to the impaired production of insulin by the pancreas, leading to elevated blood glucose levels.
There are three types of diabetes:
Type 1 diabetes
Type 1 diabetes is an autoimmune condition in which the body’s immune system attacks the β-cells of the pancreas.
This results in a lower/no production of insulin by the pancreas, thereby leading to diabetes.
Type 2 diabetes
Type 2 diabetes occurs when the body does not respond appropriately to the insulin hormone secreted by the pancreas.
This leads to the overproduction of insulin by the pancreas, causing weight gain and other complications.
Gestational diabetes
Gestational diabetes is when pregnant women without a history of diabetes suddenly become diabetic during the course of pregnancy.
How Does Metformin Affect Vitamin B12 Absorption?
Long-term usage of metformin has been known to increase the risk of vitamin B12 deficiency by affecting its absorption in the intestine.
A unique protein called intrinsic factor binds to vitamin B12 to facilitate its absorption in the intestine.
Vitamin B12 and protein complex are absorbed through a calcium-dependent membrane.
Metformin impacts the activity of this membrane, subsequently influencing vitamin B12 absorption.
Bile acid (steroid acids produced by the liver) and hepatic cells are essential for vitamin B12 absorption.
Metformin reduces the absorption of bile, resulting in the impaired circulation of vitamin B12 in the liver.
Also Read: Genes And Vitamin B12 (Cyanocobalamine) Needs
Effect Of Metformin On Vitamin B12 - The Study
The researchers at the Al-Qura University, Saudi Arabia, aimed to estimate the prevalence of vitamin B12 deficiency in type 2 diabetes patients using metformin.
The study results were published in the journal Human Nutrition and Metabolism.
206 patients with type 2 diabetes and metformin were included in the study.
Vitamin B12 serum levels of the patients were estimated.
The patients with serum levels below 243 nmol/L were defined as vitamin B12 deficient.
The patients' medical history, demographics, diet, and metformin use were also assessed.
Study Findings
- Vitamin B12 deficiency was prevalent in 17.48% of patients using metformin.
- the risk of developing metformin-induced vitamin B12 deficiency might increase with longer metformin use
- 97.2% of patients with serum B12 deficiency were using metformin for more than 2 years
- 69.4% of vitamin B12 deficient patients were receiving >1000 mg of metformin per day
Study Limitations
- The study was restricted to patients from a single hospital.
- The study adopted a cross-sectional design - considers data from one population at that particular time.
This study design may not be the best way asses the relationship between metformin usage and vitamin B12 deficiency.
- Vitamin B12 levels were measured only with serum vitamin B12 concentrations without taking into account homocysteine and methylmalonic acid levels, which offer a more sensitive reading.
Study Conclusions
The risk for vitamin B12 deficiency in people on metformin for diabetes is elevated.
This risk is influenced by metformin dosage, duration of metformin use, and occurrence and duration of diabetes.
Routine monitoring of vitamin b12 levels may be needed in people with type 2 diabetes, especially those who have been on 1000 mg/day of metformin for > 2 years.
Metformin Usage: Recommendations
- Avoid alcohol consumption while using metformin, as increased alcohol intake can elevate the risk of developing low blood sugar.
- Metformin use can cause stomach bloating and bowel side effects when taken initially. Hence, it is advised to take metformin along with meals to reduce the side effects.
- Avoid drinking grapefruit juice while you are prescribed metformin. Grapefruit juice enhances the accumulation of metformin in the liver, leading to lactic acidosis.
- Always start with a low dose of metformin and gradually increase to avoid gastrointestinal side effects.
- Consume vitamin B12-rich foods like milk, fish, eggs, fortified cereal, and tempeh to lower your risk of deficiency.
Check Your Genetic Response to Metformin with the Personalized Medicine Report
Summary
- Type 2 diabetes is a condition where the body fails to utilize the insulin hormone properly, resulting in increased blood sugar levels.
- Patients with type 2 diabetes are mostly treated with a drug called metformin.
- A recent study has reported that people with type 2 diabetes who use metformin are at an increased risk of developing vitamin B12 deficiency.
References
- https://www.sciencedirect.com/science/article/pii/S2666149722000019
- https://www.nps.org.au/australian-prescriber/articles/safe-prescribing-of-metformin-in-diabetes
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6867725/
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