Poster Presentation ESA-SRB-APEG-NZSE 2022

Time-in-range: A more intuitive measure of glycemic control in type 2 diabetes than HbA1c (#285)

Vanishri Ganakumar 1 , Madhukar Mittal 1 , Akhil Dhanesh Goel 1 , Ravindra Shukla 1 , Purvi Purohit 1 , Mahendra Kumar Garg 1
  1. All India Institute of Medical Sciences, Jodhpur, Jodhpur, RAJASTHAN, India

 

62ff514a32182-Tables.jpg

Assessment of glycemic control is shifting from HbA1c towards continuous glucose monitoring (CGM). We aimed to assess the correlation between HbA1c and time-in-range (TIR), and their relationship with coefficient-of-variation (CV%) and time-below-range (TBR) in Type-2 diabetic (T2DM) patients.

Clinical and laboratory evaluation was followed by CGM (Medtronic IPRO®2, Enlite sensor) for atleast 48-hours in 52 T2DM patients (mean age: 52.6±7.5 years) on stable lifestyle and pharmacotherapy for atleast 3-months. Median diabetes duration was 6.5 years (2-11). All patients were on oral anti-diabetic drugs, with 13.5% additionally on insulin. Median CGM readings were 831 (802-1069.5), with adequate cross-calibration with capillary-blood glucose [MAD- 9.75% (7.2-12.65)]. 

Median HbA1c and TIR were 8.8% (7.7- 11) and 59% (25-81) respectively. HbA1c had a negative correlation with TIR (ρ=-0.722, p<0.001) by Spearman’s rho(ρ) analysis; every 10% increase in TIR corresponding to a 0.59% reduction in HbA1c. HbA1c had a negative correlation with TBR (ρ=-0.396, p=0.004) and CV% (ρ= -0.312, p= 0.024), while TIR did not have a significant correlation with either variable (ρ= 0.244, p= 0.081 and ρ= 0.145, p= 0.306 respectively). Between-group analysis of HbA1c and TIR-tertiles also demonstrated this dichotomy. Higher TBR and CV% were noted in the lowest HbA1c-tertile (<8%) (p= 0.025 each), while there was no significant difference in TBR between the TIR-tertiles (p=0.36), and CV% was lower in the highest (TIR>80%) and the lowest (TIR<40%) TIR-tertiles (p= 0.003).

Thus, the “well-controlled” territories for HbA1c and TIR have divergent implications because of glycemic variability (GV) and hypoglycemia, inspite of the linear relationship between them. HbA1c suffers the bane of being an average, and directing antihyperglycemic therapy to optimize HbA1c frequently translates into higher GV and TBR. Targeting TIR instead may serve as a more intuitive measure of glycemic control and may help minimize GV and TBR-related morbidity, with long-term prognostic implications.