Open Access Te Herenga Waka-Victoria University of Wellington
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The prevalence and treatment of metformin associated Vitamin B12 deficiency in patients with type 2 Diabetes Mellitus in New Zealand

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posted on 2021-11-14, 03:09 authored by Haeusler, Sylvan

With an ever increasing incidence of type 2 diabetes in the New Zealand population, continual assessment must be made to ensure the ongoing evaluation of treatment options to ensure patient care is not compromised. Previous research has shown higher prevalence of Vitamin B12 deficiency in patients with type 2 Diabetes Mellitus who have had long term metformin treatment. An investigation into patients attending secondary care clinics at the Diabetes Clinic at Wellington Regional Hospital as well as primary health care patients has explored the prevalence of this interaction in the New Zealand population as well as assessed the factors that may contributed to such an effect. It was found that there is a high prevalence of decreased serum Vitamin B12 level in patients with type 2 Diabetes exposed to metformin treatment. Factors such as age and ethnicity were seen to be key predictors of this interaction and have shown a unique view of how the population of New Zealand may be affected. Treatment of decreased serum Vitamin B12 levels was seen to be effective through both sublingual and intramuscular methods with variations in both short and long term effects. The use of sublingual treatment administration of Vitamin B12 supplementation is unique in the scope of metformin induced Vitamin B12 deficiency and has shown potential to be a therapeutic route for patients affected by such an interactions. Current views on the interaction between metformin and serum Vitamin B12 levels are currently under debate in regards to physiological relevance and clinical outcomes. This paper provides a first look at the effect of this interaction in a New Zealand population and evaluates treatment options for such. Furthermore a proposal is made for an alternate mechanism of metformin action on Vitamin B12 levels which may aid understanding of observations made in both in this paper and previous studies.


Copyright Date


Date of Award



Te Herenga Waka—Victoria University of Wellington

Rights License

Author Retains Copyright

Degree Discipline

Clinical Research

Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level


Degree Name

Master of Clinical Research

ANZSRC Type Of Activity code

970106 Expanding Knowledge in the Biological Sciences

Victoria University of Wellington Item Type

Awarded Research Masters Thesis



Victoria University of Wellington School

School of Biological Sciences


Parry-Strong, Amber; Krebs, Jeremy