Time in Range

TIR acts as a complement to glycated haemoglobin (HbA_1c)¹ – the established gold standard for evaluating glucose control.

TIR, akin to HbA_1c, is associated with diabetes-related microvascular and macrovascular complications.^6-10 However, HbA_1c, which reflects average blood glucose levels over the past two to three months, fails to capture daily fluctuations and the variable occurrence of hypoglycaemia and hyperglycaemia.¹

Actually, patients with the same HbA_1c (7.6-7.7 %) may have very different glucose variability.¹¹

For illustrative purposes only. Not actual patient data.

CGM-derived data include quantitative measures such as Time in Range, Time above Range, and Time below Range. When combined with HbA_1c, they help healthcare professionals to quickly assess a patient’s glucose control and make more informed treatment decisions to enhance diabetes management. It enables people with diabetes to gain a comprehensive understanding of their glucose levels and provides insights into patterns of hypoglycaemia and hyperglycaemia throughout the day and night.¹

The international consensus sets clear targets for Time in Ranges.¹

§ includes percentage of values >13.9 mmol/L

§§ includes percentage of values <3 mmol/L

• The recommended glycaemic range for most people with diabetes (non-pregnant adults) is 3.0-10 mmol/L.
The 70 % target is chosen as it strongly correlates with an HbA1c goal of 7.0 %.¹
• Most people with T1D and T2D^# should spend at least 70 % (approximately 17 hours) of the day within this glycaemic range.¹
• Most people with diabetes^# are advised to spend less than 4 % of their day below range. TBR is the percentage of time spent below <3.9 mmol/L .¹ Less than 1% of the time should be spent in the “very low” TBR of <3 mmol/L .¹
• Most people with diabetes^# are advised to spend less than 25 % of their day above range. TAR is the percentage of time spent above > 10 mmol/l .¹ Less than 5 % of the time should be spent in the “very high” TAR of >13.9 mmol/L.¹

# For older and/or high-risk people with diabetes, the TIR target is lowered to >50% and TBR reduced to <1% at <3.9 mmol/L ¹

The recommendations of International Consensus Report were endorsed by the following organisations: American Diabetes Association, American Association of Clinical Endocrinologists, American Association of Diabetes Educators, European Association for the Study of Diabetes, Foundation of European Nurses in Diabetes, International Society for Pediatric and Adolescent Diabetes, JDRF and Pediatric Endocrine Society.

Studies have shown that TIR correlates with diabetes-related microvascular complications, such as diabetic retinopathy, microalbuminuria and neuropathy.^6,9,10 

In T1D, for every 10 % decrease in TIR, the progression of retinopathy has been shown to increase by 64 % and the occurrence of microalbuminuria by 40 %.¹² Also, a growing body of evidence suggests that lower TIR is associated with an increased risk of macrovascular complications, such as cardiovascular disease^7,8 and all-cause mortality in people with type 2 diabetes.⁸

Each incremental 5 % increase in TIR is associated with clinically significant benefits for people with T1D or T2D.^13,14  Every 10 % increase in TIR leads to a decrease in HbA1c of ~ 0.8 %.¹³

The FLASH-UK trial demonstrated the significant clinical benefits of the FreeStyle Libre 2 system (FSL 2) vs SMBG for people with T1D.¹⁶ The study by Leelarathna et al. (2022) was conducted as a parallel-group, multicentre, open-label, randomised controlled trial to determine the efficacy of the FreeStyle Libre 2 system vs. SMBG in improving glycaemic control in adults with T1D and suboptimal glucose control. Adults (≥16 years) n=156 with T1D MDI or CSII and HbA_1c levels between 7.5 % and 11.0 % were enrolled.

*Glucose 3.9–10.0 mmol/L ; **Adjusted mean difference vs. SMBG (95% CI, 4.7-13.3).

CSII = Continuous subcutaneous insulin infusion; MDI = Multiple daily injections of insulin; SMBG = Self-monitoring of blood glucose; T1D = Type 1 diabetes.

This study by Lameijer et al. (2023) was conducted with the objective to evaluate the impact of initiating the FreeStyle Libre system on glycaemic parameters in patients with Type 2 Diabetes.¹⁷ The design involved a retrospective analysis of de-identified data from a database of European FreeStyle Libre system users between 2014 and 2021, comprising 1,813 adults (≥18 years) with T2D on MDI (n=1,499), basal insulin (n=189), or no insulin (n=125).
After 24 weeks, significant improvements were observed across all treatment modalities, with Time in Range increasing by +2.2 to +4.7 hours per day (p≤0.003).

* Glucose 3.9–10.0 mmol/L .

MDI = Multiple daily injections of insulin; TIR = Time in Range; T2D = Type 2 diabetes.

This real-world study indicates that individuals with Type 2 diabetes and suboptimal glycemic control experience significant improvements in glycemic outcomes when using FreeStyle Libre systems—regardless of whether they are treated with intensive insulin therapy, basal insulin alone, or oral antidiabetic medications.