Should Capillary Blood Glucose Measurements be used in Population Surveys?

Objective: To determine the accuracy and appropriateness of capillary blood glucose testing in population surveys. Materials and methods: Capillary blood glucose using the Rochec ACCU-CHEK instrument and Advantage 11 Test Strips was compared to a laboratory instrument. Three independent cross-sectional risk factor surveys (n = 1432) and baseline individuals from the Greater Green Triangle Diabetes Prevention Project (n = 341) provided both fasting plasma and capillary blood glucose measurements. Accuracy of capillary glucoses was assessed using the ISO 15197 standard. The median age of the participants was 71 years, ranging from 25 to 84 years. There were 799 males and 974 females. Results: Capillary glucose method had poorer precision at lower concentrations (CV: 9.50%, mean = 3.09 mmol/L, CV: 4.90%, mean = 16.78 mmol/L, n = 233 replicates). Individual discrepancies were seen across the measuring range (2.8-19.9 mmol/L, n = 1773). In total, 94.5% of results fell within the minimum acceptable accuracy standards. This was slightly short of the 95% of results required to meet the ISO 15197 standard. The prevalence of diabetes in the study population using glucose ≥7.0 mmol/L was 2.4% (95%CI 1.8-3.3%) according to fasting plasma glucose and 2.8% (2.1-3.8%) according to fasting capillary glucose. The lower WHO-defined cut-off of 6.1 mmol/L for capillary blood glucose testing gave a prevalence of 10.7% (9.0-12.5%). Conclusions: This study of matched capillary and plasma glucose results concludes that while it is appropriate to use fasting capillary glucose levels to determine the prevalence of diabetes in populations, it should not be used to reliably diagnose diabetes in individuals.