Time In Range, as measured by continuous glucose monitor, as a predictor of microvascular complications in type 2 diabetes– A systemic review

AimContinuous glucose monitoring (CGM) derived times in range (TIR) correlates with hemoglobin A1c (A1c) among patients with type 2 diabetes mellitus (T2DM); however, there is a paucity of data evaluating its association with microvascular complications. We conducted this systematic review to examine the association between TIR and microvascular complications of diabetic retinopathy (DR), diabetic nephropathy (DN) and peripheral diabetic neuropathy (DPN).MethodWe conducted a comprehensive literature search on online database of PubMed, Scopus, and Web of Science following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Full texts original articles that evaluated association between CGM-derived TIR and risk of microvascular complications which were published between 2010 and June 2021, were included in our systematic review. The quality of included studies were evaluated using National Heart, Lung, and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Data were analyzed using qualitative synthesis.ResultEleven studies were included in the systematic review. The mean sample size, baseline A1c, and diabetes duration were 1271 (105-5901), 8.2 % (SD 0.5 %) and 11.3 years, respectively. Majority of studies were conducted in Asia (10 out 11). Four studies evaluated the relationship between CGM-derived TIR and DR and CGM-derived TIR and DN, while seven studies evaluated the relationship between CGM-derived TIR and DPN. A 10 % increase in TIR was associated with a reduction in albuminuria, severity of diabetic retinopathy, and prevalence of diabetic peripheral nephropathy and cardiac autonomic neuropathy. In addition, an association was observed between urinary albumin-to-creatinine ratio but not with estimated glomerular filtration rate.ConclusionThis review summarizes recent evidence supporting an association between CGM-derived TIR and microvascular complications among patients with T2DM. A larger□scale multi-center investigation that includes more diverse participants is warranted to further validate the utility of TIR as a predictor for diabetic microvascular complications.