Evidence-based tests to monitor adults with type 2 diabetes mellitus in primary care: rapid reviews and consensus process

Background:
When monitoring long-term conditions both over- and undertesting risk patient harm and increased healthcare costs.

Aim:
To evaluate the evidence base for type 2 diabetes mellitus (T2DM) monitoring tests and develop methods for creating evidence-based testing strategies. Design and setting Rapid reviews, consensus process. Primary care.

Method:
We identified tests that are recommended or used commonly to monitor T2DM. We created filtering questions to examine the rationale of each test, which were answered by stepwise rapid reviews of evidence cited by guidelines, systematic reviews, and individual studies. A consensus group of patient representatives and clinicians voted whether tests should be included or excluded based on the evidence or whether further evidence was needed.

Results:
Of 15 tests, only HbA1c, to monitor disease progression and treatment response, and eGFR, to detect chronic kidney disease, have a strong evidence base. Based on available evidence and consensus group feedback, routinely testing for fructosamine to monitor disease progression; thyroid function, vitamin B12, ferritin, folate, clotting, bone profile, C-reactive protein, erythrocyte sedimentation rate, and B-type natriuretic peptide; and liver function for adverse treatment effects of metformin was deemed unnecessary. We found insufficient evidence for vitamin B12 to screen for adverse treatment effects, and lipids and haemoglobin for secondary conditions.

Conclusion:
We found that the evidence-base for most T2DM monitoring tests is weak or absent. Clinicians should avoid non-evidence based tests unless there are additional clinical indications for testing. Standardised evidence-based testing panels for T2DM and other long-term conditions could reduce unnecessary testing.