Insulin pumps: Great devices, but you still have to press the button
INTERFACES ARE NOT STANDARD
When one buys a new car, little time is needed to learn how to operate it because most cars use the same basic features.
The situation is different with insulin pumps. To compete with each other, pump manufacturers create different looks, different insulin delivery methods, and different ways of administering a bolus. Switching from one pump to another is difficult without detailed education on the “bells and whistles” of the new pump.
Most patients use just a few features of the pump. They look at it as more of a convenience. They sometimes forget they are wearing it, and even forget to take a bolus before a meal.
PATIENT SATISFACTION DEPENDS ON THE PATIENT
For years, we thought insulin pumps were better at improving hypoglycemia awareness. But in a prospective study, multiple daily injections with frequent self-monitoring of blood glucose provided identical outcomes without worsening hemoglobin A1c compared with continuous infusion with real-time continuous glucose monitoring, although satisfaction with treatment was better in the latter group.4
Patients’ satisfaction with continuous subcutaneous insulin infusion depends on their baseline hemoglobin A1c level. Patients with relatively low hemoglobin A1c tend to take an active approach to self-care, describe the pump as a tool for meeting glycemic goals, and say the pump makes them feel more normal. Patients with high hemoglobin A1c tend to have a more passive approach to their self-care and have more negative experiences with the pump. Women are more concerned than men with the effect of the pump on body image and social acceptance.5
DOLLARS AND CENTS
According to 2012 estimates, 29 million Americans had diabetes mellitus, of whom 1.25 million had type 1. The direct medical costs of diabetes are estimated at $176 billion, of which 12% covers overall pharmacy costs.6 About 31% of adults with diabetes use insulin.7
For a device that costs $6,000, has a life span of only 4 years, and requires supplies that cost $300 per month, rigorous interpretation of superiority data would be needed to confirm that this technology would have a positive impact on public health if every insulin-using patient with diabetes were to say yes to it. It is true that switching from multiple daily injections to a pump leads to a significant reduction in insulin expenditures in patients with type 2 diabetes, according to a retrospective analysis of claims data.8
However, not all studies comparing pumps and multiple daily injections in type 2 diabetes have shown an advantage of one over the other in terms of a reduction in fasting glucose, hemoglobin A1c, or incidence of hypoglycemia.9 A meta-analysis10 found that the two therapies had similar effects on glycemic control and hypoglycemia. Continuous infusion had a more favorable effect in adults with type 1 diabetes.10
Neither continuous infusion nor multiple daily injections can mimic physiologic endogenous insulin secretion. Endogenous insulin is secreted into the portal system, and its main site of action is the liver. As a result, there is more hepatic glucose uptake and thus a lower peripheral plasma insulin concentration with endogenous secretion than with systemic administration. Endogenous insulin secretion also suppresses hepatic glucose production and reduces the risk of hypoglycemia.11
PROGRESS, BUT NOT PERFECTION
Diabetes mellitus constitutes a big burden on patients and on society. The discovery of insulin was a giant leap forward; the insulin pump was another great advance. We are getting closer to an integrated bionic pancreas. We are far from achieving a perfect system, but we are much better off than we were 50 or 80 years ago. And although insulin pump technology is sophisticated and precise, it still interfaces with a human user, and the human user still must press its buttons.
