HbA1c measurement using capillary blood in epidemiological studies: a scoping review of technologies and approaches

To map and describe the capillary blood-based technologies employed to measure glycated hemoglobin (HbA1c) in epidemiological studies, focusing on their accuracy, applicability, feasibility, and implementation barriers.

The development of technologies for diabetes screening and monitoring has expanded, particularly in decentralized and epidemiological contexts.

A scoping review was conducted in accordance with PRISMA-ScR guidelines. A comprehensive literature search was performed in Embase, Scopus, Web of Science, LILACS, and CINAHL between 18 and 24 February 2025. The search was conducted without restrictions on language, publication year, or geographic location, retrieving studies indexed up to 31 January 2025. We included primary epidemiological studies involving adults (≥ 18 years) that assessed HbA1c measurement using capillary blood technologies or approaches in field or population-based settings. Studies exclusively evaluating capillary glucometers, continuous glucose monitoring, or oral glucose tolerance tests were excluded. Two reviewers independently screened records and assessed full-text eligibility against pre-specified criteria registered on the Open Science Framework (OSF). Data were extracted and synthesized descriptively based on outcomes reported by the original study authors and categorized in regard to the aim.

Of 2,238 records screened, 106 studies were included. Fifteen distinct analytical technologies for HbA1c measurement using capillary blood were identified, with Point-of-Care Testing (PoCT) devices representing the predominant category. Among studies reporting diagnostic accuracy metrics, sensitivity ranged from 17.4% to 100% and specificity from 43.5% to 99.1%. PoCT devices required 2-10 µL of capillary blood and produced results within minutes. Applicability findings described portability, limited training requirements, and use in decentralized settings. Dried Blood Spot (DBS) approaches facilitated remote collection and mailing to reference laboratories. Reported challenges included variability in analytical performance, limited validation in Low- and Middle-Income Countries (LMICs), and operational constraints related to cost, supply logistics, and integration into health systems. Overall, 77% of included studies were conducted in High-Income Countries (HICs).

Capillary blood-based technologies for HbA1c measurement have been applied across diverse epidemiological contexts, with reported analytical and operational characteristics consistent with decentralized use. Nevertheless, the evidence remains geographically concentrated and heterogeneous, indicating gaps in research from LMICs.