Continuous glucose monitoring

Continuous glucose monitoring devices provide glucose readings, trends, and alerts to the user in real time to inform diabetic treatment decision making.

Continuous glucose monitoring is associated with decreases in the incidence of severe hypoglycemia and episodes of diabetic ketoacidosis in young children with type one diabetes.

Continuous glucose monitoring compared with self monitoring of blood glucose results and lowered hemoglobin A1c levels, lower rates of hypoglycemia, reduced incidence of diabetic ketoacidosis,and improved psychosocial outcomes and quality of life.

Blood glucose monitoring  systems measure an electrical characteristic, and use this to determine the glucose level in the blood. 



The test is usually referred to as capillary blood glucose.

Continue glucose monitoring shows overall benefits in adults, adolescents and young adults.

Among adults age 60 years or older with type one diabetes continue glucose monitoring compared with standard blood glucose monitoring resulting in small but statistically significant improvement in hypoglycemic events over six months (Pratley RE).


Most people with type 2 diabetes test at least once per day.


It is   recommended  that diabetics who use insulin test their blood sugar more often (4–8 times per day for type 1 diabetics, 2 or more times per day for type 2 diabetics), to assess the effectiveness of their prior insulin dose and to help determine their next insulin dose.


Blood glucose monitoring helps in the planning of meals, activities, and at what time of day to take medications, and allows for quick response to hyperglycemia or hypoglycemia.


A continuous glucose monitor determines glucose levels on a continuous basis of every few minutes.


A typical system consists of:


a disposable glucose sensor placed just under the skin


a link from the sensor to a non-implanted transmitter to a radio receiver


that displays glucose levels with nearly continuous updates.

Continuous glucose monitors (CGMs) are medical devices which extrapolate an estimate of the glucose concentration in a patient’s blood based on the level of glucose present in the subcutaneous interstitial fluid. 

A thin, biocompatible sensor wire coated with a glucose-reactive enzyme is inserted into the skin, allowing the system to read the voltage generated, and based on it, estimate blood glucose. 


Shortcomings of CGM systems, continuous systems must be calibrated with a traditional blood glucose measurement by finger stick glucose levels in interstitial fluid lag behind blood glucose values


The lag time is about 5 minutes, 15 minutes. 


The use of  continuous monitoring allows the analysis of how the blood glucose level reacts to insulin, exercise, food, and other factors. 


CGM allows for the setting of insulin dosing ratios for food intake and correction of hyperglycemia or hypoglycemia.


Use of continuous sensors is associated with less hyperglycemia and also reduces glycosylated hemoglobin levels.


The  use of test strips acts as a psychological barrier restraining the patients from sufficient glucose control.


Glucose concentrations do not have to be measured in blood vessel.


Glucose in interstitial fluid reach the same levels prevail as blood glucose, with a time lag of a few minutes due to its connection with the capillary system. 


The implantation of a sensor into the body is accompanied by growth of encapsulation tissue.


As the diffusion of oxygen to the reaction zone is continuously diminished, the decreasing oxygen availability causes the sensor reading to drift, requiring frequent re-calibration using finger-sticks and test strips.


New technologies to monitor blood glucose levels will not require access to blood.


With diabetes mellitus type 2, the importance of monitoring and the optimal frequency of monitoring are not clear. 

CGM can take a new reading as often as every 60 seconds (although most only take a reading every 5 minutes), allowing for a sampling frequency that is able to provide not just a current blood sugar level, but a record of past measurements; allowing computer systems to project past short-term trends into the future, showing patients where their blood sugar levels are likely headed.

Randomized controlled trials found that self-monitoring of blood glucose does not improve glycosylated hemoglobin (HbA1c) among reasonably well controlled non-insulin treated patients with type 2 diabetes, nor does it lead to significant changes in quality of life.


A recent meta-analysis of 47 randomized controlled trials encompassing 7677 patients showed that self-care management intervention improves glycemic control in diabetics, with an estimated reduction in their glycosylated hemoglobin levels.


Poorly controlled diabetes with HbA1C levels >8%, showed a statistically significant decrease in the HbA1C levels after a 90-day period of seven-point self-monitoring of blood glucose (SMBG) with a relative risk reduction of 0.18%.


CGM on quality of life showed no effect on patient satisfaction or the patients’ health-related quality of life. 


In the same study, patients with type 2 diabetes mellitus diagnosed greater than one year prior to initiation of CGM , who were not on insulin, experienced a statistically significant reduction in their HbA1C of 0.3% at six months follow up, but a statistically insignificant reduction of 0.1% at twelve months follow up. 


A number of studies have shown evidence that patients with type two diabetes benefit from the use of CGM in terms of improved hemoglobin A-1 C, time spent in the target blood glucose range, and reduced hypoglycemic episodes.


Newly diagnosed patients experienced a statistically significant reduction of 0.5% at 12 months follow up with CGM.


The strategy of intensively lowering blood sugar levels (below 6%) in patients with additional cardiovascular disease risk factors poses more harm than benefit.


Insulin-dependent type 2 diabetics do not need to monitor their blood sugar as frequently as type 1 diabetics.


The routine self-monitoring of blood glucose in people who are not using insulin is of limited additional clinical benefit.

Among patients with type one diabetes and high glycated hemoglobin levels, the use of intermittently scan continuous glucose monitoring with optional alarms for high and low blood glucose levels resulted in a significantly lower glycated hemoglobin level then levels monitored by fingerstick testing.



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