Postal methods for monitoring HbA1c in diabetes mellitus: a protocol for systematic review

BACKGROUND: Worldwide there are an estimated 463 million people with diabetes. In the UK people with diabetes are offered annual review, which includes monitoring of haemoglobin A1c (HbA1c). This can identify people with diabetes who are not meeting their glycaemic targets, enabling early intervention. Those who do not attend these reviews often have poorer health outcomes. During the COVID-19 pandemic, there was a 77% reduction in monitoring of HbA1c in the UK. AIM: It is hypothesised that people with diabetes could take finger-prick samples at home for measurement of HbA1c. This study will examine the agreement and correlation of capillary HbA1c values compared with a venous reference standard. It will explore reliability and repeatability of capillary HbA1c testing methods, as well as the direction of effect of storage variables. The study will also explore patient acceptability and safety. It will look at capillary blood methods that would be suitable for posting. DESIGN & SETTING: A systematic review will be undertaken. METHOD: The core terms of ‘Diabetes’, ‘HbA1c’ and ‘Capillary sampling’ will be used to search MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science Core Collection, Google Scholar, OpenGrey, and other grey literature, from database inception until 2021. Risk of bias will be assessed using the ‘COSMIN Risk of Bias tool to assess the quality of studies on reliability and measurement error’. CONCLUSION: A narrative synthesis will be produced to explore whether there are viable postal alternatives to venous sampling, as well as exploring acceptability and safety of patient self-collection.