The value of Time in Range as a diabetes tool

Time in Range (TIR) is emerging as an important new diabetes metric for both clinicians and patients that adds glycaemic detail not captured by HbA_1c. Time in Range can empower healthcare professionals and people with diabetes by providing actionable insights that can help improve diabetes management.^1,2

HbA_1c is the gold standard diabetes management tool but its limitations are increasingly apparent.^1,3 With around half of diabetes patients not meeting treatment goals, is it time to adopt a new measure of glycaemic control?⁴

Along with an inability to capture hypoglycaemia, HbA_1c provides no insight into real-time glycaemic variability (GV).³ Increasingly linked to morbidity, GV is considered by some experts to be a more meaningful measure of diabetes management.³ Furthermore, HbA_1c is only an approximate measure, and can be altered by multiple clinical and patient factors including ageing, pregnancy, anaemia, illness and medications, alcohol use and race.^5,6

TIR is one of ten core CGM metrics obtained with a continuous glucose monitor (CGM) which were agreed by international expert time in range consensus in 2019 to standardise CGM use to manage diabetes.² It reflects the amount of time spent within target glycaemic range and reveals detailed GV, for a more complete picture of glycaemic control.² For most people with diabetes, target glycaemic range is 70 to 180 mg/dL (3.9 to 10.0 mmol/L). 
A diabetes time in range target of >70% of the day corresponds to an HbA_1c of approximately 7% (53 mmol/mol), although different targets exist for different populations with diabetes, such as women who are pregnant and the elderly. and those at high risk.¹ Time in range targets are also different for gestational diabetes management.¹ Time in Range (TIR) has been heralded as a ‘new gold standard’ that is complementary to HbA_1c as a new approach to how diabetes is managed.^7,8

The CGM ‘cheat sheets’ below provide more information about using a CGM and the metric Time in Range for managing diabetes.¹ One is a reference guide to the core CGM metrics and the other is a checklist to identify patients who are suitable for CGM.

CGM metrics guide

CGM DECISION TOOL

Time in Range (TIR) provides a complete picture of glycaemic control with real-time, actionable insights

TIR has essentially evolved via self-monitored blood glucose (SMBG) testing and continuous glucose monitoring, both of which have demonstrated shortfalls without structured interpretation.^1,2,5 SMBG places a challenging burden on patients and while CGM brings the benefits of 24 -hour glucose measurements, data overload can result.^1,2,5,9 TIR, along with time below range (TBR) and time above range (TAR), is a standardised metric that can empower HCPs and patients with practical insights which enable goal setting via medication adjustments and lifestyle changes to increase time in target range²

The guide below provides a suggested framework for discussion when introducing patients to CGM and TIR.

GETTING PATIENTS STARTED USING TIME IN RANGE (TIR): A DISCUSSION GUIDE for HCPs

TIR improves both short and long-term diabetes outcomes

There is growing evidence that Time in Range (TIR) can protect against diabetes complications. TIR has been inversely associated with multiple microvascular outcomes, severe hypoglycaemia, major adverse cardiovascular events (MACE), and all-cause and cardiovascular mortality (see graph below). ^10-15

In one study, a 10% reduction in TIR was associated with an increase in retinopathy & microalbuminuria of 64% and 40% respectively.¹⁰ Another study revealed that patients achieving the recommended Time in Range (TIR) of >70% benefitted from a 31% lower risk of MACE compared to those with ≤ 50% TIR.¹⁴ Findings also suggest that Time in Range could help protect against severe hypoglycaemia.¹⁴ Investigators found a significant association between derived Time in Range and time to first severe hypoglycaemic event, with patients achieving >70% TIR having an estimated 46% reduced risk of first event compared to those with ≤50% TIR.¹⁴

Despite the clear benefits of this intuitive metric, some barriers remain to widespread adoption of Time in Range in diabetes management.¹⁶ An independent global survey of over 1,700 HCPs highlighted lack of HCP education and training as one of the top barriers to the adoption of Time in Range.¹⁶  TIR, along with TAR and TBR, is presented in the ambulatory glucose profile (AGP) report, a one-page visual summary of CGM data collected for a minimum 14 days.² Once familiar with the AGP report, HCPs can discuss TIR with patients, adjust treatment and set goals for behavioural and lifestyle changes to increase their time in range.²

The following infographic is a guide to reading the AGP by breaking it down into 3 sections.

DOWNLOAD AGP REPORT INFOGRAPHIC

Time in Range (TIR) is already proving its worth as a practical tool that supports everyday management of diabetes. Many clinicians agree that the actionable insights from TIR can inform treatment decisions and are effective for optimising insulin regimens.^2,16

Independent qualitative research shows that some people who are using Time in Range (TIR) and are familiar with the AGP in diabetes, generally find them easy to understand.¹⁷ Identifying the causes of their daily glucose fluctuations can help them feel more in control, and real-world use is showing that patients spending more time in range experience enhanced mood and a more positive mindset.^18,19

The vast majority of HCPs believe implementing Time in Range guidelines will change the course of diabetes management, enabling optimisation of insulin- and non-insulin regimens, as well as guiding prescribing.¹⁶ And TIR could also change how the efficacy of diabetes treatments are assessed; the SWITCH PRO study of the basal insulin analogues glargine and degludec was the first to use TIR as a primary endpoint in clinical research. Time in Range (TIR) was also adopted as a primary endpoint by investigators conducting the INRange comparison trial.^20,21

HQ22DI00275 June 2023