A study recently published in Medicine evaluated the link between weight-adjusted waist index (WA-WI) and diabetic retinopathy (DR).
Give me some background.
Obesity constitutes a significant global public health threat and is intricately associated with diabetes and its related complications.
Although body mass index (BMI) has historically been used to measure obesity, it fails to distinguish between muscle and fat—and is consequently prone to errors.
On the other hand: Waist circumference (WC) has been established as a reliable predictor of obesity, demonstrating a significant association with visceral fat and abdominal adiposity.
- Plus: Visceral fat has recently been identified as a more accurate marker of adverse metabolic profiles, especially those associated with abdominal obesity.
Meaning…
Consequently: A new metric of adiposity—weight-adjusted waist index—was developed to calculate weight-independent abdominal obesity by combining WC and body weight.
- In fact, recent studies have shown a link between WA-WI and rates of diabetes, along with overall and cardiovascular death rates.
However: The study authors explained that the link between WA-WI and DR remains largely unexplored.
Now to the research.
In this retrospective cross sectional study, investigators analyzed data from the National Health and Nutrition Examination Survey (NHANES) spanning from 2005 to 2018 to examine the relationship between WA-WI and DR.
In total: 2,001 subjects (1,031 men, 970 women, average age: 59.4 years) were included in the study.
Findings?
The research team found a positive association between WA-WI and DR (odds ratio [OR]: 1.32, 95% confidence interval [CI]: 1.02-1.70).
Subgroup analyses demonstrated that this relationship was more pronounced among:
- Females
- Individuals aged 50-59, 60-69, and 70+ years
- Non-Hispanic white individuals
In the general American population, WA-WI was positively associated with DR.
Expert opinion?
The study authors highlighted several potential mechanisms that could explain the observed positive association between WA-WI and DR, such as:
- Elevated WA-WI may indicate dysfunction in adipose tissue, which could facilitate the release of various proinflammatory cytokines and enhance oxidative stress
- In people with obesity, fat tissue emits higher amounts of reactive oxygen species, potentially harming the area around retinal blood vessels and leading to the onset of DR
- Being overweight has been recognized as a factor leading to insulin resistance, which can lead to metabolic disruptions that have been linked to the thinning of the retinal outer nuclear layer’s optical layers and the photoreceptor myoid zone, indicating metabolic changes in the retina related to diabetes
- Comorbid conditions associated with obesity—such as hypertriglyceridemia, impaired glucose tolerance, and hypertension—further elevate the risk of developing DR
Limitations?
These included:
- The causal relationship between WA-WI and DR could not be ascertained due to the inherent limitations of the cross-sectional study design
- WA-WI has not been widely accepted as a method of measuring obesity and central obesity in clinical settings
- The NHANES database pertains to the U.S. population, thereby limiting the geographical applicability of the study
Take home.
These findings demonstrate a positive correlation between WA-WI and DR.
And moving forward: Future studies should investigate the impact of WA-WI on diabetic complications and identify possible mechanisms.