Well controlled diabetes is not a contraindication to tummy tuck surgery and/or other elective plastic surgical procedures. Always best to check with your primary care physician or endocrinologist for “medical clearance” prior to surgery. Managing your diabetic medications around the time of surgery (to avoid hypo as well as hyperglycemia), while you will have altered oral intake, will be important. I hope this, and the attached link, helps.
Clearly you are at elevated risk for any surgical procedure and it does come down to your risk tolerance ratio. Many would advise you forego the abdominoplasty and liposuction. The possibility of wound healing problems, clotting, heart disease, etc would outweigh the benefits. Others might recommend a compromise procedure such as a panniculectomy which is less complicated than a full tummy tuck. In any case you should optimize your health prior to undergoing any elective surgical procedure It is important that your diabetes be under tight control and your Hemoglobin A1c should confirm this. Any diabetic will be at slightly higher risk than the general population for overall complications and you should be aware of this.
Being a diabetic does not disqualify a patient from elective cosmetic surgery outright. However, there are increased risks and if the medical conditions of the patient are excessive, the surgeon would advise the patient against surgery. I have operated on many diabetic patients who, besides the controlled diabetes, are in good health.