Interstitial glucose monitoring in people with diabetes Translated title: La monitorización de la glucosa intersticial en las personas con diabetes

Abstract

Devices are now available that continuously measure the interstitial glucose of persons with diabetes. They have been shown to have a very positive impact on metabolic control of the disease, with blood sugar within acceptable ranges for a longer period and a significant reduction of low blood glucose, which makes for greater patient safety and comfort 1 - 4 . These monitors are included in the service portfolio of the National Health System in Spain, and are currently financed for patients with type 1 diabetes 5 , type 2 diabetes 6 and other insulin-dependent patients (monogenetic diabetes, cystic fibrosis, pancreoprivic diabetes and hemochromatosis), as long as they are receiving intensive insulin therapy and require more than 6 finger pricks a day. A growing number of people are entering prison with these devices, which obliges professionals to familiarise themselves with how they work. There are two types of continuous interstitial glucose monitors: Real time continuous monitoring systems, with a sensor that includes a transmitter that continuously sends measurement data to the receiver, which is a mobile device, the use of which are restricted in prison. Flash monitoring systems (Figure 1), where the sensor (Figure 2) does not include a transmitter. To obtain the complete glucose history the sensor has to be scanned with the reader at least once every eight hours (Figure 3). This system is the one used in prisons. Figure 1 Flash monitoring system kit. Figure 2 Sensor of flash monitoring system Figure 3 Reader of flash monitoring system. The data in both systems is downloaded to a digital platform where it is processed via logs and graphs (Figure 4). In both cases, a set of alerts can be programmed to warn the patient of hypoglycaemia and hyperglycaemia, amongst other options. This greatly improves patient safety. Figure 4 Log and graphs of interstitial glucose data. The duration of the sensor is 6-14 days depending on the model. Wet skin and excess hair should be avoided when placing the sensor (Figure 5) 7 , because they can make adhesion more difficult; areas with lipodostrophy, scars and moles should also be avoided. A dressing is recommended to ensure that the sensor sticks to the skin, thus preventing incorrect measurements. If the patient has contact dermatitis, a protective hydrocolloid dressing or Tegaderm® dressing can be applied to the skin before the sensor is inserted 8 . Figure 5 Insertion of monitoring sensor. It should be borne in mind that when the blood glucose is stable for a period of time, there is a match in the readings for blood and interstitial glucose. If not, there is a delay between the interstitial and capillary of about 5-10 minutes. There are situations of greater instability in readings of interstitial glycaemia (postprandial period, exercise, first hours of sensor use, hypo and hyperglycaemia, etc.) that can lead to incorrect calculations of the insulin dose, and so a capillary glucose reading is recommended before making any further decisions. This measurement is also recommended in cases where symptoms appear that do not match the monitor reading. Technological advances oblige us to keep constantly up to date. They also represent a challenge to the prison system, since there is the added obligation of making prison security compatible with the right of patients to receive the same services as persons in the community.