Continuous Glucose Monitoring (CGM)

Topic for today is Continuous Glucose Monitoring or the CGM. Before we talk about CGM, let me briefly tell you about the history of glucose monitoring and how its importance was recognised centuries back. Initial attempt to identify glucose in urine dates back to the mid 18th century. Finally urine glucose testing came into effect in 1908 when Benedict developed a reagent for urine glucose monitoring. In 1945, it became more convenient with the development of a copper reagent tablet called clinitest. The first blood glucose test strip called Dextrostix was developed in 1965. This was followed by the first glucometer in 1970’s using Dextrostix. By 1980, the first dextrometer was launched which was slowly improvised with digital display over the next years. Self monitoring of blood glucose or SMBG attained significance and continued to improve by the early 2000s. The evolution of home glucose monitoring was further revolutionized with the introduction of CGM in 1999 and thereafter it was improvised every year. By 2015, it was advanced to allow data to be transmitted to the users cell phone. 

Continuous Glucose Monitoring or the CGM is the method by which blood sugar levels in patients body is automatically monitored throughout the day and night. In today’s talk I’ll focus mainly on the method of Continuous Glucose Monitoring and the devices used for this. I’m sure most of us would have heard of the term artificial pancreas. Before I go into CGMS, I shall briefly touch up on the artificial pancreas. Now artificial pancreas is a system made up of three parts that work together to mimic how a normal healthy pancreas controls and regulates blood glucose in the body. It is usually used in patients with type 1 diabetes. Three devices actually make up an artificial pancreas system. It can consist of a CGM which tracks blood sugar levels in patients using a tiny sensor inserted under the skin. Sensor sense this information into an insulin pump. The program calculates the required dose of insulin and signals the insulin pump when insulin needs to be delivered. Insulin pump delivers small doses of insulin throughout the day to the patient according to the requirement. Artificial pancreas is otherwise also known as an automated insulin delivery system or closed loop system. The benefits of artificial pancreas system is that your glucose levels will be monitored continuously. The software improves blood sugar control by automatically adjusting the amount of insulin delivers and helps keep the blood glucose under control thereby preventing hypo and hyperglycemic episodes. 

What a CGM device is, how does it work and what are its advantages in patients with type 1 and type 2 diabetes.

CGM is a device which tracks your blood glucose levels and tells you how much insulin your body needs and when. Many activities like your lifestyle, the food we eat and the exercise schedule can affect your blood sugar levels. How food or activity affects one’s glucose level is often different from how the same affects someone else. Your body response can be very unpredictable and hence makes managing diabetes very challenging even when you think you are doing everything right. Now let us know how a CGM works. You place a small sensor just under your skin, usually on your belly or arm. It is inserted very easily using an applicator and an adhesive tape holds the sensor in place. This sensor measures glucose levels in the interstitial fluid under your skin. Most sensors are waterproof and an adhesive patch keeps them firmly in place. Each sensor records blood glucose for up to 14 days after which the sensor has to be replaced by a new one. The sensor connects to a transmitter that allows the system to wirelessly send blood sugar readings. The transmitter communicates with the sensor and the  monitor and passes on the information displayed. The patient will need to sync the sensor and the transmitter with the monitor to receive readings. Some devices may have a separate dedicated monitor or part of an insulin pump. Some others are smart phone compatible and hence you receive your sugar readings on your phone.

What are the benefits of CGM and how it changes life in diabetic patients

The biggest advantage is you can literally see in real time the effects of food and exercise on your blood glucose levels and keep an eye on hyperglycemia or high blood sugar and hypoglycemia or low blood sugar as they happen. This is a big advantage over static blood glucose monitoring which only provides a single glucose reading at a time. CGMs also help to avoid the need for regular finger stick tests. It is also found to be the best outpatient method for reducing HbA1C or glycated hemoglobin. It is an easy and convenient method for monitoring blood sugars in children and for monitoring night time fluctuations in blood sugars as well as during physical activity or exercises. In patients with hypoglycemia unawareness, it helps to alert impending low sugars even when the body fails to recognise the warning signs. 

There are various models of glucose monitors available. With options available in the market, selecting the best one can be a challenge. While you choose yours, look for the most accurate one, the most consistent, durable, portability while you travel, price and affordability and overall the most easiest and comfortable to use. If you have been using a traditional glucose monitor in the past, then looking for a less painful, more easier and portable option then a CGM is a better choice.