Continuous insulin infusion: pros and cons for type 1 diabetics

This review explored the use of insulin pump systems in type 1 diabetes.

Patients with type 1 diabetes do not produce insulin, the hormone needed to break down the glucose (sugar) taken in from food. Without enough insulin, glucose can build up in the blood and can eventually lead to damage to the nerves, blood vessels, and kidneys. Treatment for diabetes involves replacing the insulin in order to keep blood glucose levels within a normal range. Insulin is most commonly replaced through multiple daily injections.

Insulin injected into the skin can be absorbed at different rates. The rate can depend on the type of insulin used (short- or long-acting), where on the body the insulin is injected or even the temperature of the injection site. For these reasons insulin levels in the bloodstream can be unpredictable. This can increase the risk of hypoglycemia (dangerously low blood glucose). Frequent episodes of low blood glucose can decrease quality of life and increase anxiety in patients. Newer methods of insulin delivery are needed that can maintain blood glucose levels.

This review examined the use of continuous intraperitoneal insulin infusion (CIPII) as a treatment for type 1 diabetes. CIPII involves an insulin pump being worn outside the body or implanted under the skin of the abdomen. With both types of pumps, insulin is continuously delivered directly into the abdomen. This type of delivery means the insulin is absorbed rapidly, allowing it to take effect more quickly.

In one study, CIPII decreased HbA1c (average blood glucose levels over 3 months) levels by 0.76% more than insulin injections. Patients using CIPII also had less hypoglycemic episodes and their glucose levels did not fluctuate as much over the day. Patients also reported higher quality of life, more treatment satisfaction and less anxiety.

CIPII use also increased production of the liver hormone, insulin-like growth hormone 1 (IGF-1). Decreased IGF-1 levels are associated with insulin resistance (meaning the body cannot use the insulin it has) and an increased risk of diabetes complications.

20% of patients using a CIPII system experienced some problems with the pump system. Common problems included blockage of the thin tube that delivers insulin, pump malfunction, or pain or infection at the site of the pump. 

This review concluded that CIPII improved glucose control and quality of life in patients with type 1 diabetes who had not achieved glucose control with insulin injections.

Insulin pumps are not currently used in a large number of patients in the United States. Future work needs to continue to compare insulin pumps to insulin injections.