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Insulin pumps: what are they and how do they work?

Insulin therapy is an integral part of treatment for many people living with diabetes.

The first insulin pumps resembling those used today became available in the 1980s. They arose from the fundamental need for people with diabetes to be able to precisely control their glycaemia (blood glucose level). 

Large-scale, long-term clinical trials have shown that careful glycaemic control considerably reduces the risk of diabetes-related complications.

Today, insulin pumps have become widely available and more and more people are using them to treat their diabetes. But what exactly is an insulin pump? What are the different parts that make it up and, above all, how is it used?

What is an insulin pump? 

An insulin pump is a medical device allowing continuous subcutaneous insulin infusion (CSII), mimicking the natural behavior of the pancreas. It enables people living with diabetes to compensate for the lack of insulin in their body; diabetes is characterised by a deficiency in the production of insulin by the pancreatic beta cells.

CSII devices comprise:

  • a small electronic pump usually connected to the abdominal wall via a flexible tube or tubing (60 to 110cm long)
  • a Teflon cannula or a stainless steel needle, allowing subcutaneous administration of insulin. 

The pump includes:

  • an insulin cartridge capable of holding 200 to 300 units of insulin
  • a display and control screen allowing the user to set various parameters, including insulin dosage and administration times.

Much like a fully functioning pancreas, insulin pumps deliver a dose of basal insulin as needed, which is then supplemented by additional boluses at mealtimes, or to correct hyperglycaemia.

Insulin Pump and CGM

Insulin dosage can be adjusted depending on the blood glucose level measured using a portable glucose meter or continuous glucose monitoring device (CGM). Some pumps are able to connect to a CGM device, allowing the user to manage changes in blood glucose more precisely than by using a glucose meter.

CGM devices consist of a sensor and transmitter, which is particularly useful for people with diabetes who may be experiencing difficulty managing hypo and hyperglycaemia. The CGM measures the glucose concentration in the interstitial fluid surrounding subcutaneous skin cells, every 5 to 15 minutes, then it transmits the data to a dedicated receiver, a mobile device (a smartphone or smartwatch) or a compatible insulin pump.

Today, insulin pumps have become more reliable, more convenient, and much smaller, thanks to progress in technology. Systems such as Bluetooth make it possible to maintain a communication link between the pump and the CGM device.

Advances in Bluetooth reduce energy requirements and thus increase the life of battery-powered insulin pumps. However rechargeable, sustainable pumps are now becoming more widely available.

How is the insulin pump used?

Insulin pump therapy is usually recommended by a specialist clinical team, but a person who is living with diabetes can discuss a move to insulin pump therapy with their team if they feel it is right for them. 

Clinical teams (doctors, diabetes specialist nurses, endocrinologists, and dietitians) will either carry out or oversee a user’s initial training on the pump, often led by a clinical specialist working with the manufacturer of the pump, and will regularly monitor a person’s use of the pump.

An insulin pump can bring more flexibility and enable people living with type 1 diabetes to manage their condition, providing key guidance is followed:

  • frequent self-monitoring of blood glucose levels (four to six times a day unless using a CGM device);
  • keeping track of the number of carbohydrates consumed during a meal;
  • working together with the clinical team and learning how to use the insulin pump correctly. 

An insulin pump delivers insulin continuously, 24 hours a day, using a fine cannula or needle inserted into the subcutaneous tissue. 

Where do you place an insulin pump?

The infusion site is usually on the lower abdomen, the outside of the thighs, hips, arms, or buttocks.

The cannula needs to be changed every 2 to 3 days and can be implanted manually or automatically, if the device includes an inserter. It is advisable to vary its position each time the cannula is changed to avoid the occurrence of lipodystrophy (accumulation or deterioration of skin fat) and infections.

 CGM sensors are also implanted subcutaneously, via a needle or a sensor. They should be replaced every 5 to 7 days.

The pump’s basal delivery rate is programmed in advance and offers the possibility of defining different flow rates at different times of day or, for example, decreasing the basal rate during the night.

Insulin pump systems are increasingly sophisticated, offering, via dedicated smartphone applications, functions for storing and displaying information. On some pumps, a bolus calculator can also be used to assess additional insulin doses according to parameters such as:

  • the blood glucose level before the meal;
  • carbohydrate intake during the meal;
  • the target blood glucose level to be achieved after the meal.

In addition, some insulin pumps also have a user and caregiver alert function, remote data access (battery charge, insulin cartridge levels, etc.), and a directory of food energy values for precise adjustment of the additional dose of insulin required before a meal.

By using all of the data recorded by the insulin pump, it is possible to optimise diabetes management and limit complications.

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  1. Ministry of health and long term care-Ontario. Continuous Subcutaneous Insulin Infusion (CSII) Pumps for Type 1 and Type 2 Adult Diabetic Populations. Ontario Health Technology Assessment Series 2009;9(20) ; octobre 2009
  2. Andrew Fry. Insulin delivery device technology 2012: where are we after 90 years? J Diabetes Sci Technol. 2012 Jul 1;6(4):947-53. doi: 10.1177/193229681200600428.
  3. I. Vecchio et al. The discovery of insulin : an importatnt milestone in the history of medecine. Frontiers in Endocrinology 23 octobre 2018
  4. B. Karges et al. Association of Insulin Pump Therapy vs Insulin Injection Therapy With Severe Hypoglycemia, Ketoacidosis, and Glycemic Control Among Children, Adolescents, and Young Adults With Type 1 Diabetes. JAMA 10 octobre 2017 ; 318 (14); 1358-1366
  5. JC. Pickup, B.M., D.Phil. Insulin-Pump Therapy for Type 1 Diabetes Mellitus. NEJM 2012;366:1616-24.
  6. Klemen Dovc, Tadej Battelino. Evolution of Diabetes Technology. Endocrinol Metab Clin North Am. 2020 Mar;49(1):1-18. doi: 10.1016/j.ecl.2019.10.009. Epub 2019 Dec 4.

About Making Diabetes Easier

Air Liquide Healthcare UK is committed to improving quality of life for people with diabetes. Our healthcare teams provide patients and their loved ones with education, support and personalisation of care.

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