# Clinician awareness and implementation of vitamin B12 monitoring guidance in metformin users: a primary care survey

## TL;DR

This study explores how well primary care clinicians in the UK are aware of and follow guidelines for monitoring vitamin B12 levels in patients taking metformin for diabetes.

## Contribution

The study identifies barriers and facilitators to implementing vitamin B12 monitoring in metformin users, focusing on clinician behavior and guidance clarity.

## Key findings

- High awareness of metformin-related vitamin B12 deficiency exists, but only 35% of clinicians had read the MHRA alert.
- Ambiguity in guidance and organizational constraints were key barriers to implementing monitoring practices.
- Facilitators included strong individual motivation and accessible resources for monitoring.

## Abstract

Vitamin B12 deficiency is a recognised adverse effect of long-term metformin use. In 2022, the United Kingdom (UK) Medicines and Healthcare products Regulatory Agency (MHRA) issued a Drug Safety Update advising clinicians to consider periodic vitamin B12 monitoring in at-risk patients. However, no specific testing interval or operational guidance has been published, and uptake within primary care remains uncertain. This study aimed to assess clinician awareness of metformin-associated vitamin B12 deficiency, evaluate the impact of the MHRA alert, and identify perceived barriers and facilitators to implementing evidence-based monitoring practices.

A cross-sectional online survey was distributed to primary care clinicians across the Southwest of England. Eligible participants included registered healthcare professionals involved in Type 2 Diabetes (T2DM) care. The validated BARRIERS scale was used to measure factors influencing evidence use, with internal consistency assessed using Cronbach’s α. Descriptive and inferential statistics, including Chi-squared and Kruskal–Wallis tests, were applied to explore associations between professional role, awareness, and testing behaviour.

A total of 124 clinicians completed the survey (approximate response rate 48%), representing a multidisciplinary primary-care workforce. Reported awareness of the association between metformin and vitamin B12 deficiency was high (87%), yet only 35% had read the MHRA alert directly, and 39% reported annual vitamin B12 testing. No significant associations were found between awareness, professional role, or testing frequency (p > 0.05). The highest mean barrier scores were within the innovation domain, reflecting ambiguity around the clarity and applicability of guidance, while the adopter domain recorded the highest facilitator scores, indicating strong individual motivation when supported by accessible resources.

Clinician knowledge of metformin-related vitamin B12 deficiency is high, but behavioural change remains limited by unclear guidance and organisational constraints. Barriers relate predominantly to the characteristics of the innovation and its implementation context rather than individual motivation. Integrating vitamin B12 monitoring into existing T2DM review templates and strengthening national guidance could enhance uptake.

The online version contains supplementary material available at 10.1186/s12875-026-03185-w.