You have not mentioned your age or having any refractory problems. If the blurring of vision occurs more frequently and associated headache there may be a refractory error. Diabetes also causes higher-than-normal blood sugar levels, which can damage small blood vessels in the eye. Many people with diabetes suffer vision complications that develop slowly over the course of their disease. High blood sugar levels can also cause temporary vision changes related to high blood glucose levels after a meal. If the meal is high in carbohydrates, blood sugar might rise to much higher-than-normal levels and take longer than usual to return to normal levels. When blood sugar levels rise, glucose accumulates in the lens of the eye. To dilute the high levels of glucose, the lens also absorbs more fluid. The extra fluid changes the shape of the lens, which can affect the ability to see. Carbs with a low-glycemic index cause a slower rise in blood sugar levels and are less likely to cause the spikes in blood sugar that can lead to lens changes. Also a blood sugar estimation is necessary. If blurriness doesn’t go away when glucose levels are close to normal, you might have retinopathy. That’s a condition in which high glucose levels damage the blood vessels in the retina. Fortunately, it’s preventable and treatable in early stages.