Time in Range According to CGM Associated With Diabetic Retinopathy

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Participants with severe diabetic retinopathy had a longer diabetes duration, higher systolic blood pressure, HDL-C, and HbA1c.
Participants with severe diabetic retinopathy had a longer diabetes duration, higher systolic blood pressure, HDL-C, and HbA1c.

The percentage of time patients with type 2 diabetes spend within a glucose range of 3.9 to 10.0 mmol/L per 24 hours, as measured by continuous glucose monitoring (CGM), is associated with diabetic retinopathy, according to a study published in Diabetes Care.

Researchers in the current study evaluated the association between time in range (defined as percentage of time within a glucose range of 3.9 to 10.0 mmol/L per 24 hours) and diabetic retinopathy, via data from 3262 patients with type 2 diabetes. They also assessed glycemic variability measures.

Of the total participants with type 2 diabetes, 780 were affected by diabetic retinopathy. Severity of diabetic retinopathy among participants was classified as either non-diabetic retinopathy (76.1%), mild non-proliferative (10.9%), moderate non-proliferative (6.1%), or vision-threatening (6.9%). 

Patients with the most advanced cases of diabetic retinopathy showed significantly less time in range and higher glycemic variability measures (P <.01). The severity of diabetic retinopathy was inversely correlated with time in range (r=-0.147; P <.001), and the prevalence of diabetic retinopathy based on degree of severity decreased with time in range increases (P <.01). 

Using multinomial logistic regression, and after controlling for sex, age, diabetes duration, body mass index, lipid profile, blood pressure, and HbA1c, researchers found significant associations between time in range and all stages of diabetic retinopathy (mild non-proliferative, P =.018; moderate non-proliferative, P =.014; vision-threatening, P =.019). Although further adjustments of glycemic variability metrics did partially attenuate these associations, the link between time in range and the presence of any degree of diabetic retinopathy remained significant.

Study investigators conclude that time in range is a more intuitive way of assessing glycemic control and provides important data that cannot be captured via Hb1Ac. They state their findings suggest that time in range “should be more broadly accepted as a research end point or clinical measure. Further prospective studies are warranted to obtain a definitive picture of the role of [time in range] in the onset and progression of [diabetic retinopathy].”

Reference

Lu J, Ma X, Zhou J, et al. Association of time in range, as assessed by continuous glucose monitoring, with diabetic retinopathy in type 2 diabetes [published online September 10, 2018]. Diabetes Care. doi: 10.2337/dc18-1131.

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