Can Gastric sleeve surgery be cancelled if sugar levels are high?

yes, it can be cancelled. and not only this type, any surgical procedure can be cancelled due to high blood glucose levels or an A1c above 6.5.

This interferes with the body's response to surgery, also influences the healing of surgical wounds, also resulting in states of post-operative hyperglycemia that are not favorable for a proper recovery and can bring with it in some cases serious complications already at the level of the organism.

But there is no need to fear if your elective surgery is cancelled for these reasons, since by consulting with an edocrinologist or diabetologist, or the doctor who follows your treatment it is possible to readjust the dosage of your medication for DM, resulting in a better management of the same and subsequently perform the surgery.

Simple answer is "absolutely!" You should be on a high protein, low carbohydrate diet before any weight loss surgery. This reduces blood sugar levels in diabetics, allows for weight loss going into surgery, and helps "shrink the liver" by reducing fatty deposits in the liver. Over consumption before surgery is not a good idea and is likely the opposite behavior told to you by your surgeon.