Advancing Insulin Therapy—An Insulin Pump or a Basal–Prandial Insulin Regimen?

How Do Patients Begin Insulin Pump Therapy?
In our clinics, we do not start pump therapy until the patient has undergone diabetes education and medical nutrition therapy. The following discussion highlights the critical role played by a CDE. The patient must know how to recognize and treat hypoglycemia and manage ‘sick days.’ Prerequisite skills include carbohydrate counting and the use of correction doses of insulin to manage hyperglycemic occurrences. After the patient has mastered these topics, he or she needs to be able to manage his or her diabetes using a basal–prandial regimen with insulin pens or syringes. This is necessary for two reasons. First, it allows the patient to learn insulin management based on a basal–prandial system that will be utilized in pump therapy. Second, the patient must know how to use pens or syringes because a back-up system must be in place if pump failure occurs. After facility with the basal–prandial approach is achieved, the pump can then be introduced and attention given to the psychomotor components of operating the pump.

Which Pump and Which Insulin?
Is one insulin pump superior to another? Probably not. Different pumps have different features and a CDE can provide much guidance on pump selection. Recommendations will be different for a child and an adult. Lifestyle requirements can enter into the decision. Some patients may opt for a disposable pump without connecting tubing, while others will select the durable units. Reservoir size, basal and bolus dosing increments, and safety features are important. Other factors include personal preferences such as the programming protocols, screen features, physical size, food menus, and communication ports for peripheral equipment such as sensors.

What type of insulin is used in pump therapy? Buffered regular insulin and the fast insulin analogs aspart, glulisine, and lispro are currently approved for use in external pumps for adults. Glulisine was recently approved by the FDA for use in children above six years of age. Most patients now use the fast analogs in their pumps because there are data showing improved post-prandial glycemic control compared with regular insulin.^32–36 Many patients have fewer episodes of hypoglycemia using aspart, glulisine, or lispro compared with regular insulin.^37–43 It is not clear if there are fewer occlusions of the tubing and needle when comparing the various insulin preparations. Some data suggest that glulisine use results in the least number of blockages,⁴⁴ but other data do not show any significant differences.⁴⁵

Achieving Glycemic Control
Glucose monitoring is essential for patients using insulin pumps or basal–prandial regimens. Without this information, there is no good way to make insulin changes. Patients with pumps often monitor their glucose six to eight times a day. Frequent interactions between the patient and diabetes team will be needed to optimize pump or basal–prandial insulin therapy. At these visits the CDE will review glycemic control, the average total daily insulin dose, number of boluses per day, and the basal–bolus insulin ratio. As the insulin requirements are adjusted, the insulin-to-carbohydrate ratio and insulin sensitivity will be recalculated.⁴⁶ The CDE will focus on the fasting glucose to make decisions on the initial basal insulin infusion rate. Glucose levels monitored one to two hours post-prandially are used to make changes in the bolus doses of insulin and provide clues about the accuracy of carbohydrate counting. Monitoring at other time-points such as before meals, at bedtime, and in the early morning gives further information on basal requirements. Sometimes only one basal infusion rate is needed, but usually two or three rates are used. More than four basal rates should signal that diabetes and nutrition education need to be re-addressed. Remember, basal insulin is needed to manage basal hepatic glucose production, which is fairly constant, and adding additional basal rates compensates for changes in insulin resistance. For example, if early-morning hypoglycemia is detected, the basal rate might decrease by 20% during the first half of the night. In patients exhibiting a dawn phenomenon, the basal rate might increase by 20% during the second half of the night.⁴⁶