Postoperative management of the diabetic patient

Diabetic patients are at increased risk for adverse outcomes of surgery. These adverse outcomes are related to pre-existing complications of diabetes, especially atherosclerotic disease, nephropathy (and perhaps increased susceptibility to other renal toxins), and peripheral and autonomic neuropathy. Hyperglycemia is associated with likely risks for poorer wound healing, increased susceptibility to infection, and probable loss of administered nutrients through glycosuria. Insulin use has the flexibility of timing and dose in the postoperative management of most diabetic patients. The combinations of intermediate-acting and long-acting insulins and short-acting insulins usually are related to the experience and preferences of the treating physicians and allied health professionals. Intravenous insulin (always R) may be limited to administration in the ICU because of the need for frequent blood glucose monitoring and rapidity of glucose response to intravenous insulin. The use of short-acting insulin analogues has been shown to work well as premeal insulin or for rapidly treating marked hyperglycemia in the outpatient setting. Meal delivery in the hospitalized patient may not be timed as precisely as in the home situation. Nurses may be responsible for many patients. The rapid-acting analogues may be associated with increased risk for hypoglycemia in the hospitalized patient if insulin cannot be given immediately before a meal. These rapid-acting insulin analogues usually are limited to circumstances in which the patient can determine the dose and self-administer just before ingestion of the meal. The long-acting insulin analogues may not afford enough flexibility in many situations in which daily dosages changes are occurring in intermediate-acting and long-acting insulins. Oral glucose-lowering agent use in the postoperative state usually is limited to selected patients, including patients who have been on such agents before surgery, who have only mild elevations of blood glucose, who are able to ingest oral medications, and who do not have significant comorbid conditions (or significant risk for such conditions) that may be contraindications to use of such agents (see Table 3). Sulfonylureas and other insulin secretagogues (e.g., meglitinide, nateglinide) lower glucoses acutely. The risk for hypoglycemia is slightly less with the nonsulfonylurea agents. Efficacy and side effects limit the use of carbohydrase inhibitors for hospitalized patients. The glucose-lowering effects of biguanides and thiazolidinediones usually are not rapid enough for hospitalized patients who have never taken these medications. For patients who have been on a biguanide or thiazolidinedione before admission, these agents often are restarted in the postoperative period when oral intake of medications is possible and hepatic and renal function are stable. The hospital period affords an opportunity to review long-term management issues related to diabetes and its complications. Instruction on the importance of medical nutrition therapy, glycemic control, management of hypertension, dyslipidemia, and aspirin use as well as basic guidelines for foot care should be carried out during the hospitalization and at the time of discharge. Similarly, appropriate arrangements for medical nutrition therapy, general diabetes education (especially for newly diagnosed diabetic patients), and regular medical follow-up are important to ensure long-term, excellent surgical and medical outcomes.