Multiple Daily Insulin Injections vs. the Insulin Pump: Where Are We Now?
I am back from vacation in Ithaca, New York, and am catching up with my journal reading. The July 22, 2010, lead article in the New England Journal of Medicine immediately caught my eye! "Effectiveness of Sensor-Augmented Insulin-Pump Therapy in Type 1 Diabetes," authored by Bergenstal, Tamborlane et.al for the STAR (Sensor-Augmented Pump Therapy for A1C Reduction 3 Study Group) has a major impact of all of our insulin dependant diabetes population.
In previous blogs, I have discussed the benefits of basal/bolus therapy with multiple daily injections vs. pump therapy. In the past, the data have been somewhat inconclusive over the long term with the exception of decreased hypoglycemia noted in those using insulin pumps. Recent research also has documented benefits to people with diabetes employing continuous glucose sensors especially in those over 25 years of age. In that JDRF study, teens did not reap the same benefits of CGMS as adults; however, the CGMS sensors must be worn to achieve usefulness. Teens are notoriously less adherent to expected utilization of these devices. Younger children faired very well with CGMS, as parents were responsible for achieving the desired goals.
In this one year randomized, controlled multicenter study, the authors compared the efficacy of sensor-augmented pump therapy (insulin pump, plus an integrated continuous glucose sensor-Metronic Minimed Paradigm REAL-Time system) with a regimen of multiple daily injections in 485 patients (329 adults and 156 children) with poorly controlled T1DM. The endpoint was a change from the baseline hb A1C. Of great importance, the study group included people with diabetes from the ages of 7 to 70 years old who had received MDI that included a long acting analogue insulin (Lantus or Levemir) during the previous 3 months and had a hb A1c between 7.5% and 9.4%. They also had to be under the care of the principal investigator or a referring physician. No people were admitted to the study if they used an insulin pump within the previous 3 years or a history of at least two severe hypoglycemic episodes in the year before enrollment.
The results were statistically significant. At 1 year, the mean hb A1c (8.3 in the 2 study groups) had decreased to 7.5% in the pump therapy group vs. 8.1% in the insulin injection therapy group (P<0.001). In the pediatric population, hb A1c decreased 0.4% in the pump therapy group and increased 0.2% in the injection-therapy group (p<0.001). The proportion of those who reached a hb A1c of <7.0% were greater in the pump therapy group. Most importantly-for both adults and children-the rate of severe hypoglycemia in the pump therapy group did not differ significantly from that in the multiple daily injection group (P=0.58). In addition, there was no significant weight gain in either group. These results are fabulous, however, as with all studies there are significant limitations. They are as follows:
- There was no blinding of medications due to the fact that medical devices were employed.
- The study did NOT compare freestanding insulin pump therapy without the sensor to sensor-augmented pump therapy to isolate the benefit of each alone or together contributing to the decrease in hb A1c.
- The authors also note that the range of hb A1c from 7.4-9.5 as inclusion criteria may limit the overall generalized significance of study results.
- People in the study were extremely motivated to adhere to diabetes self care skills (for 1 year).
- People in the sensor-augmented group received more contact initially with the clinicians due to the need for technical device training.
How do we interpret, generalize, and apply these results in the clinical setting? Is it worth all the significant time and attention to self-care skills etc. to lower a hb A1c from 8.3% (baseline) to 7.5% (sensor-augmented insulin pump) vs. 8.1% (multiple daily injections)? Overall, I think a qualified YES with certain caveats. One must be willing to use the devices as they are meant to be employed. The sensor must be worn at all times so that one can note the trending of blood sugars. Blood glucose monitoring is generally increased overall to confirm the blood glucose trends. Carbohydrate counting and bolusing must be a matter of routine and lastly, attention to insulin pump functioning and maintenance (infusion set changes, plugging information into the pump-blood sugars/carb counts etc.) must be continued. One must not underestimate the motivation required to be successful. Thus, once again, developmental factors between different age groups come into play as we have discussed many times previously. One must embrace this technology to reap the benefits. I am certain we will read more about this technology and the eventual "artificial pancreas" very soon!