Insulin protocols for hospital management of diabetes

Basal-bolus approach

Three years ago some colleagues encouraged me to introduce preprinted protocols at Kelowna General Hospital, a 350-bed tertiary care referral centre in Central Okanagan with a large complement of specialists and subspecialists but no endocrinologist. This centre has more than 100 primary care physicians involved with inhospital care of patients.

Consultations with colleagues confirmed a powerful desire to improve in-hospital diabetes management. Our main goal in introducing these protocols was to get away from the near-universal use of sliding scale regular insulin and to introduce (and simplify) the basal-bolus approach to treatment.5

Basal insulin is required to prevent fasting and unchecked between-meals hyperglycemia. Usually about 50% of the total insulin requirement, basal insulin acts by suppressing hepatic glucose output (an often forgotten but critically important source of elevated blood glucose). Basal insulin is essential even when a patient has orders for nil by mouth. Ideally a basal insulin should be prolonged, peakless, and predictable; therefore, one of the new long-lasting analogues would be preferred. Insulin NPH, although not ideal, is currently the basal insulin available on our hospital formulary and is given in the morning and at bedtime.

Bolus (or prandial) insulin is necessary to prevent a glucose surge after intake of food, thus it should have a fast and predictable onset of action, peaking at a time that coincides with carbohydrate absorption. A rapid-acting analogue is preferred and is given immediately before mealtime. In addition, a correction dose of rapid-acting insulin can be given as needed (usually at bedtime) to reduce any unexpected elevation in blood glucose.

Various protocols

Priorities in drawing up these protocols were simplicity, safety, and effectiveness. The medical protocol is designed for a non-surgical patient who is able to eat and who requires insulin. The surgical and procedural protocols cover anyone who is receiving nil by mouth and might require insulin. Doses in the protocols were arrived at empirically and largely from my own clinical experience.

Before we launched the protocols, we made a presentation to the medical advisory committee and did teaching rounds and in-services for everyone affected, including our hospitalists and staff in nursing, pharmacy, medicine, surgery, emergency, and family practice. Some fine tuning was essential. On the advice of nursing staff, “tick boxes,” which medical staff often didn’t fill in, have been removed.

Starting dose of basal insulin is intentionally conservative and, in the interests of simplicity, we purposefully omitted insulin sensitivity factors and carbohydrate counting. Surprisingly, these omissions have not proven critical; this could be because frequent review is encouraged and changes can be made at the discretion of the treating physician. It is understood that many individuals are very insulin resistant and basal-insulin requirements in particular can be several times that suggested in the protocols. Glycemic goals are as follows: fasting blood sugar, <7 mmol; 2 hours after meals, <10 mmol; perioperative range, 5 to 10 mmol.

A hypoglycemia protocol, taken from the Canadian Diabetes Association guidelines,3 is an integral part of our insulin protocols. Intravenous insulin infusion protocols are used in the intensive care unit, and occasionally on the labour floor and the renal unit.

Patient management

In-hospital patients who are competent, eating, and experienced in self-management are encouraged to continue self-managing their diabetes. Although this occasionally meets with some resistance from nursing (and medical) staff, individual expertise should be acknowledged and patients’ self-management of their diabetes should be accommodated.

Patients previously unfamiliar with the basal-bolus approach to self-management are taught on the ward. Patients are encouraged to continue with this regimen on discharge and to follow up with an early appointment at our diabetes education centre to learn more about such things as carbohydrate counting and matching bolus insulin to carbohydrate intake.