Abstract
Aim To investigate changes in the prevalence of diabetes and pre-diabetes by shifting from 2-h plasma glucose and/or fasting plasma glucose diagnostic criteria to the proposed new HbA(1c)-based criteria when applied to a Mediterranean population detected to have a high risk of Type 2 diabetes.
Methods Individuals without diabetes aged 45-75 years (n = 2287) were screened using the Finnish Diabetes Risk Score questionnaire, a 2-h oral glucose tolerance test plus HbA(1c) test. Prevalence and degree of diagnostic overlap between three sets of criteria (2-h plasma glucose, fasting plasma glucose and HbA(1c)) and three diagnostic categories (normal, pre-diabetes and diabetes) were calculated.
Results Defining diabetes by a single HbA(1c) measurement resulted in a dramatic decrease in prevalence (1.3%), particularly in comparison with diabetes defined by 2-h plasma glucose (8.6%), but was also significant with regard to fasting plasma glucose (2.8%). A total of 201 screened subjects (8.8%) were classified as having diabetes and 1023 (44.7%) as having pre-diabetes based on at least one of these criteria; among these, the presence of all three criteria simultaneously classified only 21 and 110 individuals respectively, about ten percent of each group. The single overlap index between subjects diagnosed as having diabetes by 2-h plasma glucose/fasting plasma glucose vs. HbA(1c) was 13.9/28%. Similarly, the single overlap index regarding prediabetes was 19.2/27.1%.
Conclusions A shift from the glucose-based diagnosis to the HbA(1c)-based diagnosis for diabetes will reduce diabetes prevalence with a low overall or single degree of overlap between diagnostic categories in this high-risk Spanish population.