Cataract surgery is not possible with high blood sugar. Diabetic patients with unsatisfactory blood sugar control may develop macular cystoid edema within three months after cataract surgery, which will greatly affect vision. And the site that mainly affects a person’s vision is the fundus of the eye, which is the most important site where macular occurs. Patients with excessive blood sugar are recommended to have cataract surgery, and they should first control their blood sugar and keep it within a reasonable range before they can be treated surgically. The blood sugar control index is that it must be controlled below 13mmol/L after meals and below 9mmol/L in fasting, which is the maximum limit, and surgery is not recommended above this limit.