Study Finds Link Between Body Composition, T1D Diabetic Eye Disease Risk

Waist-height ratio (WHtR), a key marker of central obesity, was associated with severe diabetic eye disease (SDED) among individuals with type 1 diabetes (T1D), according to results of a 15-year cohort study. Findings were published in The Journal of Clinical Endocrinology & Metabolism.

Diabetic retinopathy (DR) is the 5th most common cause of blindness and visual impairment worldwide, and is a common microvascular complication of diabetes, authors explained. The condition can also progress to severe stages and blindness.

Although several well-known risk factors for SDED exist among patients with T1D, it is still unknown whether central obesity is related to incidence—a pressing point as the prevalence of obesity has increased among those with T1D in past decades.

To address this knowledge gap, investigators carried out 2 separate analyses: an observational prospective study to assess the impact of anthropometric measures related to central obesity and body mass index (BMI) on the risk of SDED, and a cross sectional explore links between body composition and prevalence of retinopathy outside of SDED.

Data were gleaned from the nationwide, prospective, multicenter Finnish Diabetic Nephropathy (FinnDiane) study. SDED was defined as “proliferative diabetic retinopathy (PDR), the initiation of laser treatment or anti-vascular endothelial growth factor (anti-VEGF), diabetic maculopathy, vitreous hemorrhage and vitrectomy identified from the Care Register for Health Care until the end of 2017, whatever comes first,” authors wrote.

A total of 3468 individuals were assessed, while 437 underwent dual-energy-X-ray-absorptiometry for body composition analysis. Median (interquartile range [IQR]) age of the entire cohort was 34.8 (IQR 25.6-45.1) and a slim majority (51.2%) were female.

Analyses revealed:

• During a median follow-up of 14.5 (IQR 7.8-17.5) years, 886 SDED events occurred
• Visceral/android fat ratio was associated with SDED (odds ratio [OR] 1.40; z=3.13), as well as the percentages of visceral (OR 1.80; z=2.45) and android fat (OR 1.28; z=2.08), but not the total body fat percentage
• WHtR showed the strongest association with the SDED risk (hazard ratio [HR] 1.28; z= 3.73), followed by the waist (HR 1.01; z=3.03), body mass index (HR 1.03; z=2.33), and waist-hip ratio (HR 1.15; z=2.22)
• Results were similar in normo- and microalbuminuria, but not significant in macroalbuminuria
• A WHtR ≥ 0.5 increased the SDED risk by 28% at the normo- and microalbuminuria stages

Researchers underscored the importance of observed differences between BMI and WHtR in clinical practice as “in the present dataset, 10.7% of the individuals with normal BMI and 69.1% of the overweight people presented a WHtR ≥ 0.5, which means that several individuals at high risk of SDED would not be recognized if only a BMI ≥ 30kg/m2 would be considered as a risk factor.”

In this cohort, glycated hemoglobin (A1C) was the most important risk factor for SDED, while no anthropometric measure was associated with the risk of SDED in individuals with macroalbuminuria.

The underlying mechanism accounting for the association between visceral fat and SDED is unknown, although several hypotheses have been proposed. One of which is the fact that visceral fat produces tumor necrosis factor α (TNF-a) which studies have shown has been associated with diabetic retinopathy in patients with T1D.

Because analyses were carried out in a Caucasian-Finnish population, results may not be generalizable to other ethnicities, marking a limitation to the study.

“From a clinical perspective, this study not only highlights a new modifiable risk factor for SDED but more importantly, it shows that a simple anthropometric measure related to central obesity is associated with SDED in individuals with type 1 diabetes,” researchers concluded.

“Given that WHtR is a modifiable risk factor, our results reinforce the relevance of treating central obesity beyond blood glucose in individuals with type 1 diabetes,” they said.

Reference

Parente EB, Harjutsalo V, Forsblom C and Groop P. Waist-height ratio and the risk of severe diabetic eye disease in type 1 diabetes: a 15-year cohort study. J Clin Endocrinol Metab. Published online September 11, 2021. doi:10.1210/clinem/dgab671