Diet soda habit associated with blinding diabetes complications

Diet sodas get a dubious pass as a 'healthier' alternative to sugary soft drinks in patients with diabetes, but new evidence suggests that acceptability may go flat with frequent consumption adversely affecting the eyes.

Published online in the journal Clinical and Experimental Ophthalmology, a new study reports an association between adult patients with diabetes (PWDs) who drink more than four cans of diet soda weekly and a nearly twofold risk of having proliferative diabetic retinopathy (PDR). The reported association intrigues researchers who place increasing scrutiny on the impact artificial sweeteners may have on glucose intolerance, and opens another avenue for doctors of optometry providing timely, effective interventions.

Diabetic retinopathy, a progressive retinal disease, is the most common cause of vision loss among PWDs and a leading cause of blindness among working-age adults. The result of uncontrolled swelling in the retina from leaking blood vessels, PDR can go unnoticed by patients and if left untreated can cause severe vision loss or blindness. However, early detection and intervention through regular, comprehensive eye exams can reduce the risk of blindness by 95%.

Proper management and education helps keep patients' diabetes under control, and a large part of that involves reinforcing the importance of self-monitoring blood glucose (SMBG) and understanding the effects diet has on blood glucose levels. Researchers sought to determine how diet soda consumption—often marketed as a healthier alternative to regular soda—might influence the risk of microvascular complications. 

According to the study, researchers recruited 609 PWDs—nearly a quarter of which had PDR—from the Australian Diabetes Management Project and analyzed their food consumption, including soft drinks. Researchers found individuals consuming four-plus, 1.5 L cans of diet soda weekly had more than a twofold increased risk of having PDR. That said, diet soda consumption was not associated with higher odds of less severe diabetic retinopathy or any level of diabetic macular edema. 

"Overall, these findings support the growing body of evidence suggesting that regular and frequent consumption of artificially sweetened beverages may have detrimental vascular outcomes," the study states. Specifically, the authors note several analyses that show routine consumption of non-nutritive sweeteners may be associated with increased body-mass index and cardiometabolic risk, as well as worse cardiovascular profile in patients with diabetes. 

Interestingly, the study found no association between soft drink consumption and any level of diabetic macular edema, which authors suggest could be related to different pathophysiological processes underlying the two conditions. Moreover, the study did not find an association between regular soda consumption and presence or severity of diabetic retinopathy; however, this could be attributed to smaller numbers in the high-consumption category. 

Given the novelty of the research, authors note further longitudinal studies are necessary to determine whether diet sodas are unhealthy substitutes for regular sodas in PWDs. 

Beyond diabetic retinopathy detection 

Traditionally, optometry has acted in a triage capacity when it comes to diabetic care, detecting vascular changes and referring patients into more comprehensive or advanced care. However, times may be changing optometry's role in the multidisciplinary diabetes care team as scope of practice advances and health reform calls for a more concerted, methodical approach to patient care. 

In the November/December special issue of AOA Focus, Michael Duenas, O.D., AOA chief public health officer, says optometry is ready and able to initiate more comprehensive diabetes care that includes an emphasis on timely interventions and diabetes education through point-of-care-testing (POCT). 

"Simply put, it is past time that optometry moves beyond diabetic retinopathy detection," Dr. Duenas says. "Optometry must play a greater role in assisting a patient's glycemic control, their attainment of suitable body mass index, their reduction of cardiovascular risk factors and their avoidance of nephropathy. Furthermore, optometry must contribute to the early diagnosis and prescribed treatment of type 2 diabetes and prediabetes."  

These assertions carry the weight of a pilot study conducted collaboratively by the AOA, Johnson & Johnson Vision and Johnson & Johnson Diabetes, and presented at the 2018 National Academies of Practice Annual Meeting & Forum. That study found doctors of optometry can help traditionally noncompliant PWDs reengage self-monitoring of blood glucose (SMBG) and reconnect with their diabetes primary care provider to more effectively manage their condition. 

These findings encourage Dr. Duenas, who suggests optometry could provide even greater utility in the patient's continuum of diabetes care via POCT that leads to timely interventions, greater patient education and overall more effective management. 

"Just as optometry overcame naysayers in the past, evidence related to optometry's necessary expanding roles, combined with state and federal optometry advocacy, will make diabetic retinopathy detection a mere dotted line intended to be crossed by optometry," he says. 

Read more about optometry's evolving role in diabetes care in the November/December AOA Focus feature, "21st Century Optometric Care for the 21st Century Pandemic."