The international consensus regarding clinical targets for continuous glucose monitoring defined percentages of total time people with type 1 diabetes (PWT1D) should spend in specified glycaemic ranges. According to the statement TBR-level 1 is defined as glucose concentrations 54-69mg/dL and TAR-level 1 181-250mg/dL, which is contrary to their recommendations regarding the guidance for the assessment of glycaemic control (TBR-level 1 <70mg/dL, TAR-level 2 >180mg/dL). The aim of this retrospective observational study was to assess if this discrepancy leads to different results for time spent in glycaemic ranges.
PWT1D (n=100, 49 female vs. 51 male, HbA1c 7.4±0.8%; age 42±14 years, 19 CSII, 81 MDI) used a flash glucose monitoring (FlashGM) system for 3 months from which >80% of the sensor data were available. FlashGM data were compared depending on the aforementioned recommendations via paired t-tests (p≤0.05) (Table 1).
Table 1
Standardized CGM metrics for clinical care | Guidance for glycaemic targets | p-value | ||
TBR-level 2 <54 mg/dL | 2.0±2.2% | TBR-level 2 <54 mg/dL | 2.0±2.2% | n/a |
TBR-level 1 54-69 mg/dL | 3.6±2.3% | TBR-level 1 <70 mg/dL | 5.6±4.3% | p<0.0001 |
TIR 70-180 mg/dL | 55.1±15.8% | TIR 70-180 mg/dL | 55.1±15.8% | n/a |
TAR-level 1 181-250 mg/dL | 24.0±7.5% | TAR-level 1 >180 mg/dL | 39.3±17.1% | p<0.0001 |
TAR-level 2 >250 mg/dL | 15.3±11.3% | TAR-level 2 >250 mg/dL | 15.3±11.3% | n/a |
100±0% | 117.3±11.1% | p<0.0001 |
Our results showed a difference between the standardized CGM metrics for clinical care versus guidance for glycaemic targets hence leading to different percentages in pre-specified glycaemic ranges.