Peter Attia· MD
a classic example of this is someone will point out hey you know my vision my glasses prescription suddenly changed it i became much more nearsighted or i became much more farsighted in the space of a month and i i went to the eye doctor and they said wow your glasses are totally wrong and the first thing i think of is go get your blood sugar checked because glucose can diffuse into the lens cause it to swell and that will change the shape of the lens the lens becomes physically bigger so it's like a thicker more powerful lens so it's an osmotic chain correct basically and the the time frame for that to happen is over a period of several weeks so if the blood sugar goes up it may there may be a lag of a month or two before the vision changes and when the blood sugar goes down same thing it takes weeks for that to kind of go back to normal