Evaluation of vitamin B12 monitoring in patients on metformin in urban ambulatory care settings

Trends in Vitamin B12 Level Testing in Patients on Metformin From 2000 to 2020

Background and Objectives

Metformin is one of the primary pharmacologic agents for managing type 2 diabetes mellitus (T2DM). However, it has been associated with interference in vitamin B12 absorption and deficiency. Vitamin B12 deficiency and T2DM can present diagnostic challenges for polyneuropathy. Diagnosis is essential for guiding treatment, yet the use of vitamin B12 level testing in this population may have dwindled over time amid changing practice guidelines. This study examines trends over time in the use of vitamin B12 level testing among patients on metformin.

Methods

This retrospective trend analysis used data from TriNetX, a real-world, longitudinal clinical database. Patients treated with metformin from 2000 to 2020 were identified using Rx Concept Unique Identifier codes. The number of patients who underwent vitamin B12 level testing at any time after 1 month from metformin initiation was tabulated. Patients were grouped by the year of B12 level testing. Trends in B12 level testing were assessed using the Jonckheere-Terpstra statistical test (P<.05).

Results

Out of 4,203,020 patients prescribed metformin, 1,055,995 (25.1%) underwent B12 level testing. The highest proportion of patients tested was in 2000 to 2002 (39.6%), while the lowest proportion was in 2018 to 2020 (20.1%). B12 testing utilization declined significantly by 19.5% from 2000-2002 to 2018-2020 (P=.001).

Conclusions

In this study, we found that the use of vitamin B12 level testing in patients on metformin has significantly declined over the years, potentially impacting early detection of B12 deficiency. Future studies with more granular data from real-life practice are recommended to understand the precise reasons and impact of this trend.

Bidirectional association between diabetic peripheral neuropathy and vitamin B12 deficiency: Two longitudinal 9-year follow-up studies using a national sample cohort

AIM

This study aims to investigate the association among metformin use, vit B12 deficiency, and DPN occurrence in diabetes.

METHODS

This retrospective, propensity-matched cohort study was performed using National Health Insurance Service database - National Sample Cohort in South Korea. Study 1 analyzed DPN incidence according to vit B12 deficiency and study 2 analyzed vit B12 deficiency incidence according to the presence/absence of DPN. Moreover, we compared the results with respect to metformin use.

RESULTS

In study 1, DPN incidence per 10000 person-year (PY) was 179.7 and 76.6 in the vit B12 and non-vit B12 deficiency groups, respectively. The adjusted HR was 1.32 (95% CI; 1.21-1.44, P < 0.05) and metformin use elicited a more significant effect of DPN occurrence in patient with vit B12 deficiency (HR: 5.76 (95% CI; 5.28-6.29). In study 2, vit B12 deficiency incidence per 10000 PY was 250.6 and 129.4 in the DPN and non-DPN groups, respectively. The adjusted HR was 2.44 (95% CI; 2.24-2.66, P < 0.05), however, metformin prescription was associated with the reduced incidence of vit B12 deficiency in DPN patients (HR 0.68 (95% CI; 0.62-0.74, P < 0.05).

CONCLUSION

DPN occurrence increased in diabetes with vit B12 deficiency and the incidence of vit B12 deficiency was also high in DPN patients. However, metformin showed opposite effects in both cohorts. Further studies clarifying the causal relationship among DPN occurrence, vit B12 deficiency, and metformin use are warranted.

Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial

AIM

To investigate the effect of normalizing vitamin B12 (B12) levels with oral B12 (methylcobalamin) 1000 μg/day for one year in patients with diabetic neuropathy (DN).

PATIENTS AND METHODS

In this prospective, double-blind, placebo-controlled trial, 90 patients with type 2 diabetes on metformin for at least four years and both peripheral and autonomic DN were randomized to an active treatment group (n = 44) receiving B12 and a control group (n = 46) receiving a placebo. All patients had B12 levels less than 400 pmol/L. Subjects underwent measurements of sural nerve conduction velocity (SNCV), sural nerve action potential (amplitude) (SNAP), and vibration perception threshold (VPT), and they performed cardiovascular autonomic reflex tests (CARTs: mean circular resultant (MCR), Valsalva test, postural index, and orthostatic hypotension). Sudomotor function was assessed with the SUDOSCAN that measures electrochemical skin conductance in hands and feet (ESCH and ESCF, respectively). We also used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE, respectively) and questionnaires to evaluate quality of life (QoL) and level of pain (pain score).

RESULTS

B12 levels increased from 232.0 ± 71.8 at baseline to 776.7 ± 242.3 pmol/L at follow-up, p < 0.0001, in the active group but not in the control group. VPT, MNSIQ, QoL, pain score, SNCV, SNAP, and ESCF significantly improved in the active group (p < 0.001, p = 0.002, p < 0.0001, p < 0.000, p < 0.0001, p < 0.0001, and p = 0.014, respectively), whereas CARTS and MNSIE improved but not significantly. MCR, MNSIQ, SNCV, SNAP, and pain score significantly deteriorated in the control group (p = 0.025, p = 0.017, p = 0.045, p < 0.0001, and p < 0.0001, respectively).

CONCLUSIONS

The treatment of patients with DN with 1 mg of oral methylcobalamin for twelve months increased plasma B12 levels and improved all neurophysiological parameters, sudomotor function, pain score, and QoL, but it did not improve CARTS and MNSIE.

A review of therapeutic options for managing the metabolic aspects of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age. Metabolic sequelae associated with PCOS range from insulin resistance to type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). Insulin resistance plays a significant role in the pathophysiology of PCOS and it is a reliable marker for cardiometabolic risk. Although insulin sensitising agents such as metformin have been traditionally used for managing metabolic aspects of PCOS, their efficacy is low in terms of weight reduction and cardiovascular risk reduction compared with newer agents such as incretin mimetics and SGLT2 inhibitors. With current pharmaceutical advances, potential therapeutic options have increased, giving patients and clinicians more choices. Incretin mimetics are a promising therapy with a unique metabolic target that could be used widely in the management of PCOS. Likewise, bariatric procedures have become less invasive and result in effective weight loss and the reversal of metabolic morbidities in some patients. Therefore, surgical treatment targeting weight loss becomes increasingly common in the management of obese women with PCOS. Newer emerging therapies, including twincretins, triple GLP-1 agonists, glucagon receptor antagonists and imeglemin, are promising therapeutic options for treating T2DM. Given the similarity of metabolic and pathological features between PCOS and T2DM and the variety of therapeutic options, there is the potential to widen our strategy for treating metabolic disorders in PCOS in parallel with current therapeutic advances. The review was conducted in line with the recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome 2018.