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Insulin Pumps and CGMs Basics

On occasions, a patient who has been appointed the use of insulin pumps and CGM machines might not turn out to be the best candidate for them. In order to determine if these types of machines are safe and ideal for an individual to take on, he/she should be aware of the basics of each of these two. The following information can help current or potential users of insulin pumps and CGMs to conduct an informed conversation with their physician about their employment.

“In the early 1960s, Dr. Arnold Kadish developed the first insulin pump, which was the size of a Marine backpack. Over the years, insulin pumps have become much more refined and have decreased in bulk to the size and weight of a small pager. Insulin pump therapy, also known as continuous subcutaneous insulin infusion, is no longer seen as experimental and controversial, but rather is viewed as an acceptable alternative to multiple daily injection (MDI) therapy in the management of insulin-dependent diabetes.”1 

Insulin Pumps and CGMs are small and portable machines that help to maintain a degree of control over the glucose levels in the blood. Its use is recommended to those who live with a lack of hormone insulin or those who have to deal with the body’s resistance to it. Users of these machines have been vocal about the positive effects on their health condition. Both gadgets are known to make glycated hemoglobin results fall to a lower level, as well as to lead to a decline of the normal blood sugar levels. In extremely positive cases, users have been able to change their blood sugar levels to reach the numbers usually expected from individuals without diabetes.

“Insulin pump treatment reduces the frequency of severe hypoglycemia compared with multiple daily injections treatment. The addition of a continuous glucose monitor (CGM), so-called sensor-augmented pump (SAP) treatment, has the potential to further limit the duration and severity of hypoglycemia as the system can detect and in some systems act on impending and prevailing low blood glucose levels. […] There are currently 2 generations of SAPs on the market: in the first, the insulin dosing software operates independently of the CGM values so that the user has to make basal rate adjustments manually; in the second, the insulin dosing software and the CGM values are coupled which allows for automated suspension of basal insulin delivery in response to a predicted or detected low glucose level. For both SAP generations, however, meal and correction insulin delivery must be manually controlled, preferentially supported by the use of the insulin pump bolus calculator software.”2 

Insulin Pumps

“The insulin pump is an electromechanical device that mimics the body’s natural insulin secretion from pancreatic β-cells by subcutaneously delivering rapid-acting insulin both at preset continuous basal rates and in extra bolus doses at mealtimes on demand. Insulin pumps allow for up to 24 different hourly basal rates in a 24-hour period. For bolus doses, pump users input their current blood glucose level and the number of carbohydrates they will consume, and the pump customizes their dose based on insulin currently on board (i.e., the remaining active insulin from the previous dose), their individualized insulin-to-carbohydrate ratio, and their individualized insulin sensitivity factor (i.e., their expected drop in blood glucose from 1 unit of insulin). Thus, insulin pumps are able to deliver insulin in a more physiological manner than other injection-based insulin regimens.”3 

Insulin Pumps are helpful for periodically administering minimum quantities of insulin. The type of insulin utilized is one that immediately evokes a response on the body. This appliance administers insulin through the midriff. The substance is transferred from the machine into the midriff by a long and slim hollow cylinder. Insulin pumps are attached to electronically powered gadgets that allow the recording of blood sugar levels. Depending on the type of insulin pump, the user will be able to maximize the amount of substance he/she receives when blood glucose levels rise. 

Pump Therapy
Pump Therapy


“Pump therapy entails infusion of short-acting insulin (typically NovoRapid or Humalog) from a reservoir within the pump via plastic tubing into a fine-bore cannula placed in the subcutaneous tissue. The cannula is typically sited on the abdominal wall although other areas can also be used, and needs to be changed every 3 days. The cannula can be inserted by hand or by utilizing a purpose-designed device. In most models, the needle component of the cannula is removed after insertion, leaving a very fine plastic tube sitting in the subcutaneous tissues. CSII (continuous subcutaneous insulin infusion therapy) delivers insulin in two patterns: a pre-programmed continuous background insulin infusion (the rate usually varies over the 24-h period), with additional insulin boluses for food or to correct hyperglycemia. People using CSII do not take any additional long-acting insulin: both background and bolus insulin are delivered by the pump. The basal infusion rates are pre-programmed by the patient or his/her diabetes specialist but can be adjusted by the touch of a button. Basal insulin will continue to run until the insulin cartridge is empty. Insulin boluses are delivered as required under the patient’s direction; most pumpers make use of an inbuilt ‘bolus calculator’, which utilizes known variables for that individual (insulin: carbohydrate ratio, insulin sensitivity, and target blood glucose range) in conjunction with situation-specific data (current capillary glucose level, estimated carbohydrate intake and time since last insulin bolus). The pump and tubing can be removed for up to 1 h leaving the cannula in situ, for example for swimming, bathing or contact sports, such as boxing or rugby. Some pumps are waterproof and, therefore, can be kept on for prolonged aquatic pursuits.”4 


CGM machines are specifically designed to track glucose levels at regular intervals. The machine notifies when blood sugar numbers go through abnormal changes. The notification comes in the form of a sound which indicates the user needs more insulin or should consume more carbs. CGM machines are able to notify glucose levels thanks to a discrete sensor that should be attached to the midriff area.

Continuous glucose monitoring systems (CGMS)
“Continuous glucose monitoring systems (CGMS). (A) Dexcom SEVEN® Plus, (B) Dexcom G4TM, (C) Guardian REAL-time, (D) FreeStyle Navigator®, (E) FreeStyle Navigator II, (F) HG1-c and (G) GlucoTrackTM.”5


What is the Downside of Owning Insulin Pumps and CGM machines?

Benefits of these gadgets are numerous, including the ability to be aware and to control blood sugar levels. Therefore, they can minimize the incidents of glucose levels in the blood dropping or rising to abnormal quantities.

Although they have many points at their favor, its benefits will not be apparent on every user.

These machines can be costly to purchase, keep and use on a regular basis. The physician should be aware of the user’s financial boundaries before deciding on these gadgets, since usually the insurance fails to cover these monitors.

If the user is able to afford these gadgets, then learning how to properly manage them can be confusing and difficult. Therefore, there are users who might experience difficulties when making sense and making use of either insulin pumps or CGM machines.

“People using CSII (continuous subcutaneous insulin infusion therapy) do not take any additional long-acting insulin. Therefore, any interruption to insulin delivery from the pump (eg if the tubing has an air block or the cannula is kinked or dislodged) results in immediate insulin deficiency. Hyperglycemia and DKA (Diabetic ketoacidosis) can develop quickly, unless the problem is identified and rectified, for example by re-siting the cannula, refilling the insulin reservoir, changing the tubing, or by starting alternative insulin, such as an intravenous infusion. Technical problems with the pumps can occur; the pump manufacturing companies offer round-the-clock telephone support and are typically able to provide a replacement pump within 24 h if required. All patients using pumps are advised to retain a supply of their pre-pump insulin for use in an emergency situation, for example, in case of pump failure or damage.”6 

Why is it Important to Be Knowledgeable about Insulin Pumps and CGM machines?

After conducting careful research the user is able to offer an informed opinion to his/her physician about the use of these gadgets. It is important to be aware of the product general attributes before discussing it with an expert in the field. After a conversation in which both parties are able to understand the terms, the physician will be able to determine if these gadgets are ideal for the patient. This is based on the user’s ability to afford them and the general impact it will have on his/her health status.

“The benefit of using CGMS is clearly evident from sensor augment pump (SAP) therapy, which involves the combining of CGMS with the insulin pump. It demonstrated a significant reduction in HbA1c level, improvement of glycemic control and critically reduced severe hypoglycemic and hyperglycemic events in patients with type 1 diabetes mellitus in a rapid, sustainable and safe manner. The type 1 diabetics, who had a high HbA1c level and were older at diagnosis and randomization, experienced the most benefit from SAP therapy. The subjects treated by SAP therapy for 12 months reported significantly less hospitalization, increased treatment satisfaction and reduced fear of hypoglycemia. It was further demonstrated that the beneficial effects of SAP therapy persist, even after 36 months of its start. The HbA1c level decreased from 8.7% to 7.3% from the time when the SAP therapy was started to the end of 36 months (p < 0.0001). A study demonstrated that the initiation of CGMS before subcutaneous insulin infusion increases the CGMS frequency use in type 1 diabetes mellitus patients and significantly reduces the time spent in hypoglycemia.”7  

“Diabetes has become a global epidemic during the last two decades. It is increasing at an alarming pace of 7.8 million new diabetics each year and is taking an unsustainable economic toll, amounting to 11.6% of the total healthcare expenditure. The ongoing research efforts to find the cure for diabetes by developing an artificial pancreas or by islet cell transplantation will take a lot of time based on the challenges involved and only a very limited scope for success. The current use of intensive insulin treatment is inadequate, as it leads to a marked increase in episodes of severe hypoglycemia. Moreover, insulin treatment is not expected to dramatically reduce the formation of Amadori products, which have a major impact on secondary health problems. Therefore, more frequent glucose monitoring is the only way to effectively manage diabetes by sustaining the physiological blood glucose level.”8  



(1, 3) Insulin Pump Class: Back to the Basics of Pump Therapy. Wilson Reece, S. & Hamby Williams, C.L. Diabetes Spectrum. 2014. 

(2) Sensor-Augmented Insulin Pumps and Hypoglycemia Prevention in Type 1 Diabetes. Steineck, I., Ranjan, A., Nørgaard, K. & Schmidt, S. Journal Of Diabetes Science and Technology. 2016. 

(4, 6) Insulin pumps in hospital: a guide for the generalist physician. Evans, K. Clinical Medicine. 2014. 

(5, 7, 8) Continuous Glucose Monitoring Systems: A Review. Kumar Vashist, S. Diagnostics. 2013. 


María Laura Márquez
13 October, 2018

Written by

María Laura Márquez, general doctor graduated from The University of Oriente in 2018, Venezuela. My interests in the world of medicine and science, is focused on surgery and its greatest advances. Nowadays I practice more:

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