Basal Bolus Therapy: MDI vs. Insulin Pumps
Treating type 1 diabetes requires the administration of insulin. Different insulin regimens are available to meet the unique needs of each family based on differing life circumstances. It is clear, however, insulin regimens that attempt to match pancreatic functioning will provide the tightest possible glycemic control.
Basal/Bolus therapy most closely matches the manner in which the pancreas secretes insulin. At present, there are two modes of basal/bolus delivery: multiple daily injections (MDI) to match carbohydrate ingestion and to lower blood sugar and insulin pump therapy in which insulin is delivered continuously. For many families, however, insulin pump therapy is simply not an option because the child/adolescent does not wish to have a device always attached to the body or for other personal reasons.
When asked which form of insulin therapy is better, my answer is always couched in the same terms: choose the insulin regimen that will provide the best adherence for your child. In theory, the child/family may wish to use pump therapy; but after realizing that a catheter must be placed and changed every 2-3 days, pump therapy may not be the most desirable option. Clearly, the decision to choose MDI or Pump therapy is a personal one, but must be made based on evidence-based research.
Over the past few years, the literature has been very consistent. Insulin pump therapy provides excellent glycemic control with the least amount of hypoglycemia. The key in this sentence is hypoglycemia; as MDI will also provide nearly the same glycemic control in terms of hb A1c, but there will be a greater risk of hypoglycemia based on previous studies.
A very recent study was published in the journal Diabetologia documenting the longest and largest study of insulin pump therapy in children. Johnson, Cooper, Jones and Davis published "Long-terms outcome of insulin pump therapy in children with type 1 diabetes assessed in a large population -based case control study" (Diabetologia "¨DOI 10.1007/s00125-013-3007-9). The goal of this Australian study was to "determine the impact of insulin pump therapy on long- term glycemic control, BMI, rates of severe hypoglycemia and diabetic ketoacidosis in children."
The study population consisted of 345 children on insulin pump therapy in a single pediatric hospital who were matched to children treated with MDI. The variables studied included age, diabetes duration, and hb A1c at time of pump start. Information including "anthropometric data," episodes of severe hypoglycemia and rates of DKA requiring hospitalization were collected after the start of the study (prospectively).
What were the results? (Statistical significance: p<0.05)
- Average age: 11.4 years
- Duration of diabetes at pump start: 4.1
- Length of follow-up: 3.5 years
- No significant BMI change in the pump group
- Mean hb A1c reduction in the insulin pump group was 0.6%
- The improved hb A1c remained "significant" throughout a 7- year follow-up period
- Insulin pump therapy reduced severe hypoglycemic episodes from 14.7 to 7.2 events/100 patient years (p<0.001)
- In the MDI group, the rate of severe hypoglycemic episodes (in the same period) increased from 6.8 to 10.2 events/100 patient years
- The rate of hospitalization for DKA was lower in the pump group: 2.3 vs. 4.7/100 patient years (p=0.003) over the 1,160 patient years of follow-up
What may we conclude?
This Australian study is the longest and largest study of insulin pump use in children. Based on the above results, pump therapy provides a sustained improvement in glycemic control (but not statistically significant). There were reductions of severe hypoglycemia (statistically significant) and hospitalization for DKA was, indeed, lower for those using the insulin pump (statistically significant).
There are limitations to this study in view of the fact that, according to the authors, the first 100 pump patients were a select group in which there could be a potential selection bias_._ In addition, this was not a randomized trial, rather an observational case-controlled study. Another possible reason for decreased episodes of DKA in the pump group may be due to increased education and increased motivation in those that choose to move to the insulin pump.
In summary, my final comments will restate what I attested to previously. The most important key to diabetes management is the motivation to maintain glycemic stability with a hb A1c based on your diabetes team recommendations, without a significant increase in hypoglycemia and hospital admissions for DKA. This study suggests that there is a decrease in hb A1c (no statistical significance) with an associated decrease in hypoglycemia and hospitalizations for DKA (with statistical significance) employing insulin pump therapy. Thus, if one is willing to move and adhere to insulin pump therapy with the accompanying requirements, it may be worth considering. As always, before changing insulin regimens, please discuss the pros and cons with your diabetes healthcare team.
Fran Cogen, M.D., C.D.E., is the director of the Childhood and Adolescent Diabetes Program at Children’s National Health System. She wrote about diabetes for HealthCentral.