Introduction: Standardized meals have been suggested as a potential tool to diagnose glycemic disorders. In obese patients with different glycemic status (normal glucose tolerance (NGT) or intermediate hyperglycemia (IH: IFG and/or IGT), or type 2 diabetes (T2D), we aimed to examine the relationship between the glucose response to 75g OGTT and a “French” standard breakfast test including 75g carbohydrates, and between the glucose response to both tests with insulin resistance (IR) and glucose variability (GV) derived from continuous glucose monitoring (CGM).
Patients and Methods: We included 80 obese patients without known dysglycemia, separated according to OGTT in 24 NGTs, 37 with IH and 19 T2Ds. Several IR indexes were calculated. GV was evaluated by calculating SD-glucose, CONGA, J index and MAGE from 24h CGM including the OGTT on day 1 and the standard breakfast test on day 2.
Results: Using CGM data, the 120-minute area under curve (AUC-glucose) and glucose peak were similar after OGTT and breakfast, the time to the interstitial glucose peak was longer (p<0.02) and glucose 2 hours levels higher after OGTT than after breakfast (p<0.001). AUC-glucose after OGTT and breakfast correlated with 24h GV indexes respectively on days 1 and 2 (p<0.001), with IR indexes including HOMA-IR and FIRI, and negatively with QUICKI, ISI0min, ISI120min, Gutt and Matsuda indexes (p<0.02 to 0.0001). Most of 24h GV indexes correlated with several IR indexes (p<0.01 to 0.0001). All T2Ds, 35 out of the 37 patients with IH and 3 of the 24 NGTs had either glucose 60 or 120 minutes after breakfast ≥7.8 mmol/l, giving a 96% positive predictive value to predict abnormal results during OGTT.
Conclusion: In obese patients without known dysglycemia, the magnitude of glucose excursion after the standard breakfast correlates with the glucose response to OGTT, 24h GV and IR. This more physiological test offers a good performance to predict abnormal response to OGTT.
A. Rezki: None. M. Fysekidis: None. E. Cosson: Board Member; Self; Abbott, Boehringer Ingelheim Pharmaceuticals, Inc., LifeScan, Inc., Lilly Diabetes, Medtronic, Merck Sharp & Dohme Corp., Novartis France, Novo Nordisk A/S, Roche Diagnostics France, Sanofi. Research Support; Self; Air Liquide, Lilly Diabetes, Novo Nordisk A/S, Roche Diagnostics France, Roche Foundation, Sanofi. P. Valensi: None.