Self-monitoring of blood glucose level: control mechanism and motivational engine
The body’s sugar metabolism is impaired in diabetics. Possibly permanently. However, if those affected monitor their blood regularly and adhere strictly to their doctor’s advice, it is usually possible to get the metabolism back to normal.
With every foodstuff, carbohydrates are broken down in the gastrointestinal tract and released into the blood. The glucose extracted is an important supplier of energy for the body’s somatic cells. The pancreas measures the blood glucose level. If this is too high, it releases the hormone insulin so that the glucose can enter the somatic cells. If it is too low, glucagon is released. This hormone mobilises sugar reserves in the body.
People with diabetes have either a shortage of their body’s own insulin (a complete shortage in some cases) or its effect is limited. The consequence of this is a high blood glucose level. Cells become damaged if the blood glucose level remains permanently high,
Haemoglobin A1c (HbA1c) is a very important parameter for assessing the metabolism and monitoring diabetes over a long period. Haemoglobin is the red blood pigment where blood glucose accumulates. The higher the blood glucose level and the longer it is at a high level, the higher is the long-term blood glucose level HbA1c.
People who monitor their blood values regularly prolong their lives
It is therefore very important to measure blood values. The so-called ROSSO (Retrolective Study Self-Monitoring of Blood Glucose and Outcome in Patients with Type 2 Diabetes) study1 involved over 3,000 type 2 diabetes patients throughout Germany and was carried out between November 2003 and June 2004 by the German Diabetes Center in Düsseldorf and the Profil Institut für Stoffwechselforschung in Neuss. The study revealed that the probability of suffering physical damage was about a third lower in the group of patients who always monitored their blood glucose level regularly than in the group that never undertook such monitoring. And even the mortality rate in the former group was only half that in the latter. The reason can be explained quickly: over time they had discovered what behaviour had a positive or a negative effect on their blood glucose levels.
The result was similarly positive for type 2 diabetics who were not insulin users. The ROSSO study had thus demonstrated that self-monitoring of the blood glucose level can significantly improve the life expectancy and quality of life of patients with type 2 diabetes.
Self-monitoring of blood glucose level increases the motivation for therapy
A recent study2 from China involving type 2 diabetes patients who were not receiving insulin therapy substantiates the ROSSO result. Not only did the researchers there examine the HbA1c value: they also looked at the body mass index (BMI), blood pressure, blood lipid levels and waist circumference. Their conclusion: regular self-monitoring of the blood glucose is of benefit not only to patients who have recently been diagnosed but also to those who have suffered from diabetes for a year or more. The initial HbA1c value does not matter; however, the benefit of self-monitoring of the blood glucose was greatest when patients had a value below 8.0 per cent.
The fact that self-monitoring of the blood glucose leads to a significant reduction in the HbA1c value for type 2 patients not receiving insulin therapy, as shown by the study, demonstrates that self-monitoring of the blood glucose is not merely an important control mechanism. Rather, it is an important incentive to continue with the therapy and pursue a healthy lifestyle because it is carried out regularly and the results are immediately visible for those affected. Regardless of whether it is carried out with or without insulin therapy, self-monitoring of the blood glucose level motivates patients and thus und brings about a detectable improvement in their condition.
And this is how self-monitoring of the blood glucose level is carried out
With the help of a lancing device, diabetes patients obtain a drop of blood from the side of a fingertip and spread this on a test strip. The strip is then inserted into a small device, which measures the current blood glucose concentration and displays it within less than a minute.
The German Diabetes Association (DDG) classifies HbA1c values as follows:
- no diabetes: less than 39 mmol/mol (below 5.7 per cent)
- suspicion of diabetes: 39 to 47 mmol/mol (5.7 to 6.4 per cent)
- diabetes: 48 mmol/mol or more (6.5 per cent or more)
The frequency of monitoring the blood glucose depends on the medical diabetes therapy but also on how strongly the values fluctuate. Type 2 diabetics usually take medication that lowers the blood glucose but does not cause low blood sugar (hypoglycaemia). In such cases, it might suffice if the doctor measures the blood glucose and the long-term value every three to six months.
The situation is different for diabetics who must inject insulin. To determine the quantity required, they should measure their blood glucose level up to seven times a day (before and after their main meals and before going to bed), as well as when they suspect that their blood glucose is too low – also when they want to drive a car, of course.
For anyone who injects insulin in quantities specified by the doctor and has stable glucose levels, it might suffice to adhere to a diurnal profile for a week, for example before and two hours after a meal and before going to bed. The diurnal profile should be written down so that the doctor can see whether the therapy should continue or must be changed.
Continuous glucose measurement
Besides devices for measuring ‘normal’ blood glucose levels, it is also possible to measure the glucose content of the interstitial fluid of the subcutaneous fatty tissue using a continuous glucose monitoring (CGM) system. A glucose sensor is inserted under the skin, where it can remain for up to seven days and call up the glucose content every five minutes. A small sender attached to the arm transmits the data to a display system. The CGM can be combined with an insulin pump.
There are medical prerequisites regarding the use of such a device. Furthermore, an application must be made to the Medical Service of the Health Funds (MDK), and ultimately approved by it.
1 Zhu H, Zhu Y, Leung S (2016): Is self-monitoring of blood glucose effective in improving glycaemic control in type 2 diabetes without insulin treatment: a meta-analysis of randomised controlled trials, BMJ Open 2016;6:e010524, http://bmjopen.bmj.com/content/6/9/e010524.
2 Zhu H, Zhu Y, Leung S (2016): Is self-monitoring of blood glucose effective in improving glycaemic control in type 2 diabetes without insulin treatment: a meta-analysis of randomised controlled trials, BMJ Open 2016;6:e010524, http://bmjopen.bmj.com/content/6/9/e010524.