Clinical Pearls: Soda Effect

One clinician’s observation of the effect of drinking both diet and regular sodas on the health of the patient. The observations and data acquired via clinical practice using electronic medical records and high resolution digital andiogram system for 25 years.


When dealing with diabetic retinopathy, most physicians would tell a person with diabetes that the “real” sodas (with sugar) are not good and that the diet ones are alright. Many years ago, I became aware that there were patients that would get good treatment for diabetic macular edema (at that time focal laser) that would improve the edema, but 4-6 months later would be back with similar or new edema (DME) that needed repeat treatment. There were at least two general classes of DME: one was the “focal edema” that had microaneurysms and focal leakage that did well with focal laser to the offending microaneurysms.  The second type of DME was the “diffuse edema” that did not do well with focal laser and did not have a good treatment strategy. Grid laser was typically applied to these patients with mixed results. Medicine goes though “phases” of ideas that either pan out or are forgotten as they really did not work long term. One such phase was the use of Diamox (acetazolamide or carbonic anhydrase inhibitor) for diffuse DME. It seemed to work about 50% of the time but did not cure the problem. Other issues that made this treatment fall out of favor was the fact that it could loose serum potassium and needed occasional serum K+ checks. Some of my patients at that time stated that the vision improved on Diamox but could not stand drinking sodas when taking the drug. There were others that kept on drinking sodas anyway and their therapeutic response to Diamox was very poor. They would complain however that while on Diamox the sodas did not taste good due to a metalic taste but still kept on with their habit of drinking sodas.

One day there was a paticularly poorly compliant diabetic patient with florid diffuse DME and worse than 20/200 vision. He was very allergic to sulfa drugs and had a history of kidneystones. There were several reasons not to use Diamox. I questioned him on his soda drinking habits and discovered he was drinking about 2 liters of diet soda a day. On a whim, I asked if he could stop the sodas altogether and just drink the same fluid volume but water instead. Within a month the diffuse DME had subsided with only a change in his drinking habit. I came to realize that the side effect of Diamox use, namely the change in the taste of sodas, seems to make some patients stop their long standing soda drinking habit, causing the DME to improve while others did not stop drinking them and did poorly.

In the early 1990’s I wrote my own electronic medical record system. I also developed my own very high resolution digital fluorescein angiogram system (FA) and I started to look at the images of the diabetic patients. I became about 70% accurate in the ability to look at the FA images and tell the patient what their soda consumption was. There was focal constriction of the pre-capillary arterioles that I noticed as well as the size of the foveal avascular zone and general capillary drop out on the images. Further analysis of the electronic medical records showed a correlation of soda drinking to hypertension, renal failure and heart disease. Now as retina specialists we tend to use intraocular steroid and anti-vegf injections for these patients, while some may be reversed by a diet change of eliminating sodas first rather than having injections, with cost and the complications of drug intervention. The risk is minimal to stop the sodas, the benefit may be avoiding costly drug use and organ damage. There are multiple patients with advanced renal failure that were drinking multiple liters of diet sodas and when they quit drinking them, their renal failure progression stopped or started to reverse to the consternation of the nephrologist. The soda “quitters” had about a 10-15 point drop in the average BP without a change in the medications.

For decades I have tried to scientifically prove this but do not have a good metic to measure soda consumption to be able to do a good study. I also noted that stopping soda consumption has no risk and could at least save the patient some money on sodas in the case of “no effect”. If this soda effect is true, this could have serious ramifications on the well being of the patient. Really no down side to stopping sodas, possibly no effect or very significant up side effect. So do we really need to prove this or just try it with your patients and see for yourself if this rings true?

PS: My EMR/database ran flawlessly for 23 years and when I last checked it had >1765 soda questionares in the database. Unfortunately, the data was not collected in a standard manner as needed in a study. It evolved as observations were made. I am open to suggestions on how to prove this relationship, thanks for listening and please leave your thoughts…

CapDU PDRRecBetter yet, try getting your patient to stop the soda consumption and watch what happens. Let me know!

Sincerely PVH

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