Using CGM-Derived TIR to Predict Microvascular Complications in Type 2 Diabetes

A systematic review of data related to continuous glucose monitoring in type 2 diabetes suggests time in range measured by a continuous glucose monitor could help predict risk of microvascular complications in this patient population.

The systematic review, which included 11 studies with more than 13,000 patients, provides insight into associations of diabetic nephropathy, diabetic peripheral neuropathy, and diabetic retinopathy with time in range among patients with type 2 diabetes.

“To our knowledge, this is the first systematic review examining the relationship between CGM-derived time in range and microvascular complication among patients with type 2 diabetes mellitus,” wrote investigators.

For the purpose of analysis, investigators performed a comprehensive literate search of the PubMed, Scopus, and Web of Science databases on June 5, 2021, for studies published from 2010 to June 2021. For inclusion, studies needed to be published in English. Search terms used in the query included continuous glucose monitoring, continuous glucose monitoring, Dexcom, Freestyle Libre, Guardian, flash glucose monitoring, time in range, time-in-range, or TIR, diabetes complications, microvascular complications, retinopathy, neuropathy, nephropathy, complication, microalbuminuria, or albuminuria, and type II diabetes or type 2 diabetes.

The initial search identified 110 publications for possible inclusion. After exclusion of duplicates and further screening, a group of 11 articles were identified for inclusion in the systematic review.

These 11 studies included a population of 13,987 patients, with a median sample size of 466 (range: 105-5901, IQR: 616). Of the 11 included, 10 were cross-sectional in design and the remaining study was an interim analysis of an ongoing prospective observational study. The study population had a mean of 59.3 (SD, 1.3) years, the mean HbA1c at baseline was 8.2% (SD, 0.5%), and the mean duration of diabetes was 11.3 (SD, 1.0) years.

A group of 4 studies examined the association between time in range and diabetic retinopathy. In these 4 studies, results indicated a 10% increase in time in range was associated with a reduction in severity of diabetic retinopathy and increased time spent in target range was associated with a decrease in the severity of diabetic retinopathy. Investigators also pointed out time-in-range was similar to HbA1c for predicting diabetic retinopathy in patients with type 2 diabetes.

Similarly, a group of 4 studies examined the association between time-in-range and diabetic nephropathy. In these studies, a 10% increase in time-in-range was associated with a decrease in albuminuria. Additionally, a single study demonstrated increased time-in-range was associated with a lower risk of macroalbuminuria and diabetic kidney disease.

A total of 7 studies assessed the relationship between time-in-range and diabetic neuropathy while 4 studies examined time-in-range and diabetic painful neuropathy. Analysis of these studies indicated increased time-in-range was associated with a decrease in the prevalence and severity of diabetic painful neuropathy and cardiovascular autonomic neuropathy.

“Our study affirms the significant association between CGM-derived TIR and microvascular complications of diabetic nephropathy, diabetic retinopathy, and diabetic painful neuropathy among patients with type 2 diabetes mellitus,” wrote investigators.

This study, “Time in range, as measured by continuous glucose monitor, as a predictor of microvascular complications in type 2 diabetes: a systematic review,” was published in BMJ Open Diabetes Research and Care.