Schmidt MI, et al. – In this study, researchers examined the prognostic properties of five definitions of intermediate hyperglycemia, or prediabetes, to predict its progression to diabetes. They noted better sensitivity with impaired fasting glucose (IFG), according to criteria from the American Diabetes Association (ADA) vs criteria from other guidelines, such as the World Health Organization (WHO). However, it classified approximately half of adults with intermediate hyperglycemia and poorly predicted diabetes.

Methods

• The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) was an occupational cohort study that consisted of active or retired civil servants aged 35–74 years.
• Individuals who provided inadequate data to estimate the diabetes status, those without information on relevant covariates, and those with diabetes were not included in the study.
• They categorized type 2 diabetes on the basis of self-report, medication use, measures of fasting plasma glucose (FPG), 2-hour plasma glucose level, and HbA_1C.
• They used 5 laboratory definitions of intermediate hyperglycemia: IGT (2-hour plasma glucose ≥ 7.8 mmol/L [≥140 mg/dL]); IFG based on American Diabetes Association criteria (FPG ≥ 5.5 mmol/L [≥ 100 mg/dL]); IFG based on WHO criteria (FPG ≥ 6.1 mmol/L [≥ 110 mg/dL]); HbA_1c based on American Diabetes Association criteria (HbA_1c ≥ 39 mmol/mol [5.7%]); and HbA_1C based on International Expert Committee criteria, IEC- HbA_1C, (HbA_1C≥42 mmol/mol [6.0%]).
• Risk of each definition was measured using Cox regression, and overall predictability (area under the receiver operating characteristic curve [AUC]) was assessed using logistic regression.

Results

• The study sample consisted of 15,105 participants who were followed up for a mean of 3.7 years.
• The diabetes incidence rate was 2.0 per 100 person-years.
• A total of 59% of 11,199 eligible participants presented with some form of intermediate hyperglycemia.
• Diabetes was poorly predicted with ADA-IFG, IEC- HbA_1C, and ADA- HbA_1C.
• Greater conversion was predicted with WHO-IFG and IGT.
• They found either low sensitivity or specificity in all the definitions.
• The investigators reported that combinations of tests improved prognostic characteristics, with the combination of IGT or WHO-IFG showing the best, but still inadequate, predictability.
• They recorded the AUC for the three underlying glycemic tests as follows: 65.0% for HbA_1C, 74.6% for FPG, and 77.1% for 2-hour plasma glucose.
• The AUC for a score composed of clinical information was 71.6%
• The AUC reached 82.4% when this score was combined with results of an oral glucose tolerance test.