Abstract P428: Risk-Based Approach to Defining Prediabetes Among Middle-Aged Adults in the Atherosclerosis Risk in Communities (ARIC) Study

Abstract

Introduction: Current prediabetes definitions, based on fasting blood glucose (FG) or HbA1c, are broad and capture many individuals who will never develop diabetes. Other risk factors including age, sex, body mass index (BMI), systolic blood pressure (SBP), and family history of diabetes, are not part of current definitions but are highly predictive of progression from prediabetes to diabetes. We evaluated whether approaches to defining prediabetes that incorporate standard clinical measures can improve 10-year diabetes risk prediction. Methods: We conducted a prospective analysis of 11,322 participants in the Atherosclerosis Risk in Communities (ARIC) Study aged 46-70 years (55% women, ~20% Black adults) without diabetes at baseline (1990-1992). We used logistic regression to develop risk equations for incident diabetes over ~10-year based on combinations of HbA1c, FG, and/or clinical measures (age, sex, BMI, SBP, family history of diabetes). We calculated area under the curve (AUC) for 10-year diabetes risk, comparing American Diabetes Association (ADA) prediabetes definitions (HbA1c 5.7-6.4%, FG 100-125 mg/dL, either, or both) with our new risk equations. Results: Over ~10 years of follow-up, there were 1230 incident cases of diabetes. The ~10-year absolute diabetes risk for persons with HbA1c 5.7-6.4% was 27% (AUC=0.66) and for persons with an FG of 100-125 mg/dL was 16% (AUC=0.64). Risk equations combining FG and HbA1c yielded an AUC of 0.76. The additional inclusion of all 5 clinical measures increasing the AUC to 0.78 (ΔAUC=0.02; p<0.001). Simple clinical measures, primarily BMI, led to modest improvements in risk discrimination when added to HbA1c alone (ΔAUC=0.03; p<0.001) or FG alone (ΔAUC=0.03; p<0.001). Conclusions: Defining prediabetes based on both an elevated FG and elevated HbA1c (confirmatory definition) or using clinical variables (age, sex, BMI, SBP, family history) added to either FG or HbA1c can substantially improve our ability to identify middle-aged adults who will progress to diabetes.