For people with diabetes, increasing time spent in the target glycemic range—Time in Range (TIR)—may help to reduce the risk of diabetes-related health complications.1-5
Dr. Richard Bergenstal, International Diabetes Center, Minneapolis, explains why TIR is becoming an important metric for diabetes management.
While A1C and self-monitoring of blood glucose are valuable tools for assessing glucose control, research shows that approximately one out of two people with diabetes are not achieving the recommended A1C targets in Canada when using A1C.6 In addition, many people with diabetes* currently spend less than half of their day in range—which is significantly lower than the TIR target of at least 70% for most people with diabetes.7-13
TIR has been shown to inversely correlate with the risk of onset or progression of diabetes-related microvascular complications, such as diabetic retinopathy, microalbuminuria, and neuropathy.1,2,5 For example, for every 10% decrease in TIR, retinopathy progression has been shown to increase by 64% and microalbuminuria occurrence by 40%, in type 1 diabetes.14 Growing evidence shows that lower TIR is also associated with an increased risk of macrovascular complications, such as cardiovascular disease3,4 and all-cause mortality in people with type 2 diabetes.4
Frequency of developing microvascular complications according to level of TIR (3.9–10 mmol/L) computed from quarterly seven-point blood glucose testing.
A: Retinopathy B: Microalbuminuria
Blood glucose concentrations were measured at a central laboratory from seven finger stick samples (seven-point testing: pre- and 90-min postmeals and at bedtime) collected during one day every three months. Retinopathy progression was assessed every six months and urinary microalbuminuria development every 12 months.14
Building a more proactive patient/healthcare professional relationship through data
TIR is a clinical metric that enables people with diabetes to monitor their day-to-day glycemic variability.13 After food choices, TIR is considered the second most important factor that affects the daily life of people with diabetes.15
Using TIR with other continuous glucose monitoring (CGM) metrics, including Time Below Range (TBR), Time Above Range (TAR), mean glucose levels and glycemic variability, offers deeper insight to help people with diabetes understand their glucose targets and daily glucose profile.13
“TIR, together with CGM, is a very powerful metric to make patients’ visits more useful. It puts power in the hands of people with diabetes. Doctors worry, at first, that TIR can increase consultation time, but it saves time.” Dr. Alice Cheng, University of Toronto, Canada.
Dr. Alice Cheng, University of Toronto, explains how TIR is a useful metric and conversion tool in clinical practice.
This additional layer of data complements A1C to offer insight into the potential drivers behind daily fluctuations in glucose levels and the occurrence of hypoglycemia and hyperglycemia. This insight empowers people with diabetes to actively manage their diabetes and adopt positive lifestyle adjustments to improve glucose control.13
For healthcare professionals, TIR provides an opportunity to have informed conversations with people with diabetes about factors that may have led to out-of-range readings, such as food choices and physical activity,15 treatment choice, and dosage and timing of insulin.13 When used together, A1C and TIR can help people with diabetes and healthcare professionals build realistic and effective management strategies to spend longer periods of time within a target range.13