It is not uncommon for patients to say their vision fluctuates from day to day, or even in the same day. The lens of the eye sits right behind the pupil and focuses the incoming light on the retina. When blood sugar levels are high this lens tends to swell slightly. As a result it focuses the light too much. If you wear glasses and they were prescribed when the sugar was high they will be wrong when the sugar is low, and vice versa.
Diabetic patients are probably a little more likely to get cataracts than other people.
It often filters out some of the colors. Much can be done to prevent and treat diabetic eye disease. Since you have a personal interest, it is essential you take charge of your diabetes management. As always, early detection is the key. Insist your vision be tested and your eyes examined regularly by someone who dilates your pupils to study the condition of your retina.