Blood sugar levels and vision

Does anyone monitor blood sugar levels along with vision? Is there any good research on the subject?

I know being diabetic can cause many eye issues. My own eye issues have at least been compounded from historically being diabetic.

At one point a few years ago I used to take my blood sugar level daily. I kept my mmol/l in the 4 to 6 range and have done so for about 30 months now, with some exceptions such as christmas.
Today I consider myself to be an ex type 2 diabetic and rarely eat added sugars.

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I’m also curious about this! To add a very soft data point, I’ve noticed that I can see better after eating than before. For example, I might not have clear flashes before eating, but after I will. Could this could be related to blood sugar levels?

I found this study “Stable refraction and visual acuity in diabetic patients with variable glucose levels under routine care”
Conclusion: Refraction and visual acuity test results were highly reproducible and stable in patients with reasonably well controlled diabetes but variable blood glucose levels under routine care.

But after reading further:
“In nine (of 53) patients with less stable refraction, the mean variability was 0.40 D.” Those patients weren’t very stable but it seems the blood glucose level wasn’t correlated. A 0.40 D change in one month seems large to me! I wonder what the cause was…

It would be interesting to see a study conducted where the goal was vision improvement through slight visual challenge, like the Reduced Lens Method, comparing diabetic to non-diabetic participants and monitoring blood sugar levels for all. That study would control the stimulus to the eye. I’m most interested in the influence on the rate of adaptation (~0.75 Diopters/yr for most individuals, it seems) that blood sugar levels have.

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Good for you for licking Type II diabetes.

Haven’t personally been able to find any research on sugar, insulin, or ketosis as relates to vision. Either it doesn’t exist or my search skills leave much to be desired. I have read two sources (Jake and Annette Bosworth, MD) that speak to it, but neither referenced research as far as I could tell.

There is lots in relation to vision in general, for example diabetics have a correlation with cataracts, glaucoma, blurry vision and retinopathy.
The Myopia Manual summarises that in relation to myopia :
Section 3.24.1 3.24.1 - Carbohydrates, Blood Sugar Level, Insulin Metabolism, page 165-168 (pdf page 177-180)
Section Blood Sugar Level / Insulin Level, page 246 - 248 (pdf page 258-260)


Maybe just being diabetic, which seems to mean you have high variable blood sugar levels and corresponding vision variablity which is why I’d like to know if blood sugar levels in non diabetics could have a similar effect on vision.

Refractive changes in diabetic patients duringintensive glycaemic control (pdf)
This was rather shocking “In a study of 10 eyes of five diabetic patients, bilateral transienthyperopia with a maximum refractive change of between 1.1 and 4.9 dioptres, occurred after initiation of strict hypoglycaemic control”

Also related, again a study on diabetics, Gradients of refractive index in the crystalline lens and transient changes in refraction among patients with diabetes (pdf)


That is totally nuts!

Believe the answer to that is yes. Here’s why.

My start on EM coincided with a two week fast, during which I experienced the following improvement:
L: -4.50/-2.00 R: -3.50/-2.50 < Starting point
L: -3.03/-0.67 R: -3.03/-0.67 < Last day of fast

Now I know big improvements are to be expected in the first three months, but two weeks?

What happened next is why I think you’re onto something:
L: -3.57/-0.60 R: -3.23/-0.77 < One week post-fast
L: -3.70/-0.64 R: -3.57/-0.78 < Two weeks post-fast
L: -3.23/-0.77 R: -3.03/-0.67 < Nine weeks post-fast

Though the rapid initial drop could be attributable to newbie gains, what would explain the reversal? Following that two-week reversal improvements started registering again, going back to the gradual changes you’d expect.

Not sure if it’s the glucose, response to glucose (insulin), ketosis, or all of the above, but something’s going on there.


Quotes are from Refractive Changes in Diabetic Patients During Intensive Glycaemic Control.

It seems the patients were wearing negative correction.
“If a new prescription for glasses is made at that time, there is a possibility that the new glasses will soon become inadequate.”
We know that lenses induce a change in axial length. Maybe the effect is amplified by blood sugar changes? This would explain Astigmatism_Assasin’s results.

“Regarding the effect of chronic changes in plasma glucose, myopia associated with hyperglycaemia and hyperopia with hypoglycaemia have been reported to develop in diabetic patients.”

Here’s a hypothesis:
Given that the eye adapts to stimulus, the eye becomes decreasingly sensitive to far-stimulus when hyperglycaemic causing an adaption that brings about myopia; and the eye becomes decreasingly sensitive to close-stimulus when hypoglycaemic causing an adaption that brings about hyperopia.

(Alternatively, the eye could become more and not less sensitive to the opposite stimulation and maybe achieve the same thing)

I think the hypothesis can explain Astigmatism_Assassin’s two-week gains reversal. Maybe once the fast was ended the blood sugar swung to the other end and stayed there a little while.

What do you guys think?
How stable is blood sugar in non-diabetic people? If the hypothesis is not false… is this something we can leverage in combination with Reduce Lens to bring about emmetropia more rapidly?


If I’m understanding the study correctly there is initial vision improvement - less negative correction necessary - during treatment for hyperglycemia, but it is transient, i.e. if new glasses are prescribed during treatment they soon become inadequate. For instance with the patient below (from the study), if new glasses are prescribed at the maximum point of improvement in week four, positive diopter changes being improvement, the new prescription thereafter becomes progressively too weak:

They seem to rule out the usual suspects (note axial length):


The only thing that seems to be missing in the above statement is the visual cortex. My own pet theory is that glucose/insulin somehow adversely impact optimal optical cortex functioning.

What’s also interesting is the transient nature of the change and I wonder what impact diet post-treatment has on regression. The only discussion of diet is calorie restriction during treatment, there is no discussion of diet post-treatment. If glucose and/or insulin are indeed the culprits you would expect a strict ketogenic diet to be beneficial in preserving improvements.

Perhaps it is time for another self-experiment.


See also this study on food restriction and visual cortex plasticity (referenced in the EM article on intermittent fasting):


I was just reading about this the other day
Good news for me I’ll be fasting next May for a month. I hope by then I have already done a few reductions and the fasting will help keep the improvement and not plateau. :innocent: