Continuous Glucose Monitoring and 1-hour Plasma Glucose Identifies Glycemic Variability and Dysglycemia in High-Risk Individuals with HbA1c <5.7%

Abstract Purpose: Although commonly used, HbA1c is insensitive for diagnosing prediabetes and diabetes. Glycemic variability (GV) or a 1-hour plasma glucose level (1-h PG) ≥ 155 mg/dL (8.6 mmol/L) during a 75-gram oral glucose tolerance test (OGTT) better identifies individuals with dysglycemia. The objectives were to (1) compare continuous glucose monitoring (CGM) with the OGTT for detecting dysglycemia in high-risk subjects with HbA1c < 5.7% (39 mmol/mol), and (2) correlate the 1-h PG with CGM-derived GV indices. Research Design and Methods: Subjects (n=15) with a HbA1c < 5.7% (39 mmol/mol) and at least one other risk factor for type 2 diabetes such as overweight, obesity, hypertension, or hyperlipidemia were recruited. A 2-h OGTT was performed within 3-7 days of CGM insertion, which was worn up to 14 days. Results: The average age was 50 ± 14 years, with the majority of participants being men (80%) and Caucasian (67%). The mean HbA1c was 5.3±0.2% (34 mmol/mol). The 1-h PG was highly correlated with 1-h CGM glucose levels (ρ=0.881, p<0.001) as well GV indices: mean amplitude of glucose excursions (ρ =0.67, p<0.01), standard deviation (ρ=0.79, p<0.01), and lability index (ρ =0.64, p=0.001). Conclusion: 1-h interstitial CGM glucose and 1-h PG can detect dysglycemia in high-risk subjects with HbA1c < 5.7% (39 mmol/mol). CGM may be an alternative screening tool for glucose disorders.