[citation needed] Continuous monitoring allows examination of how the blood glucose level reacts to insulin, exercise, food, and other factors.

While the technology has its limitations, studies have demonstrated that patients with continuous sensors experience a smaller number of hyperglycemic and hypoglycemic events, a reduction in their glycated hemoglobin levels and a decrease in glycemic variability.

[16] In a recent systematic review with meta-analysis about glycaemia monitoring in critical patients[17] who are haemodynamically unstable and require intensive monitoring of glycaemia it concluded that should be undertaken using arterial blood samples and POC blood gas analysers, as this is more reliable and is not affected by the variability of different confusion factors.

However, an increasing number of insurance companies do cover continuous glucose monitoring supplies (both the receiver and disposable sensors) on a case-by-case basis if the patient and doctor show a specific need.

[citation needed] The principles, history and recent developments of operation of electrochemical glucose biosensors are discussed in a chemical review by Joseph Wang.

[18] Investigations on the use of test strips have shown that the required self-injury acts as a psychological barrier restraining the patients from sufficient glucose control.

A significant improvement of diabetes therapy might be achieved with an implantable sensor that would continuously monitor blood sugar levels within the body and transmit the measured data outside.

The burden of regular blood testing would be taken from the patient, who would instead follow the course of their glucose levels on an intelligent device like a laptop or a smartphone.

[citation needed] Glucose concentrations do not necessarily have to be measured in blood vessels, but may also be determined in the interstitial fluid, where the same levels prevail – with a time lag of a few minutes – due to its connection with the capillary system.

Since the implantation of a sensor into the body is accompanied by growth of encapsulation tissue,[20] the diffusion of oxygen to the reaction zone is continuously diminished.

This decreasing oxygen availability causes the sensor reading to drift, requiring frequent re-calibration using finger-sticks and test strips.

[31] A new implantable continuous glucose monitor based on affinity principles and fluorescence detection is the Eversense device manufactured by Senseonics Inc.

[citation needed] Most[citation needed] of the non-invasive methods under development are continuous glucose monitoring methods and offer the advantage of providing additional information to the subject between the conventional finger stick, blood glucose measurements, and overtime periods where no finger stick measurements are available (i.e. while the subject is sleeping).

Furthermore, the same study identified that patients with type 2 diabetes mellitus diagnosed greater than one year prior to initiation of SMBG, who were not on insulin, experienced a statistically significant reduction in their HbA1C of 0.3% (95% CI, -0.4 – -0.1) at six months follow up, but a statistically insignificant reduction of 0.1% (95% CI, -0.3 – 0.04) at twelve months follow up.

[44] A recent study found that a treatment strategy of intensively lowering blood sugar levels (below 6%) in patients with additional cardiovascular disease risk factors poses more harm than benefit.

[citation needed] Blood glucose monitoring is, in that case, simply a tool to evaluate the success of diet and exercise.

[49] A randomized controlled trial evaluated once-daily self-monitoring that included tailored patient messaging and did not show that this strategy led to significant changes in A1C after a year.