Glucose Levels and Diabetes

Diabetes is a health condition where the conversion of food into energy is compromised. The food that enters the body gets broken down into glucose and enters the bloodstream. The glucose is then transported to the cells with the help of a hormone called insulin, to provide energy for cellular functions.

However, it can happen that either insulin production is affected in the body or there is a malfunction in the use of the insulin by the body which results in excessive glucose left in the bloodstream. This is termed diabetes. Diabetes can have symptoms like thirst, frequent urination, fatigue, blurry vision, and more. It can also lead to long-term complications of cardiovascular issues, chronic kidney disease, issues with vision, and nerve damage. On the other hand, conditions like chronic kidney disease could lead to diabetes, too.

Measuring Glucose from Blood

An important step in treating diabetes is monitoring glucose levels. The most common and widely used technique is measuring the amount of glucose in the blood periodically. In the blood, glucose can attach to a protein called hemoglobin which is part of the red blood cells. It is termed as glycated hemoglobin or HbA1c. The red blood cells have an average lifetime of 2 to 3 months. Hence, the glucose levels measured using this method are an average value of glucose over time which gives a bigger picture of glucose levels and changes.

For those who are already diabetic, at-home glucose monitors are available that involve a skin-prick blood test. This gives an instantaneous value of the glucose level in the blood and can depend on the food eaten or activity done before taking the measurement. Logging these measurements over time is more useful and will give a better understanding of the changes in glucose levels.

Measuring Glucose using a Continuous Glucose Monitoring Device

Continuous glucose monitoring is a wearable technology that helps keep track of glucose level changes over time, from minutes to days or months. The device contains a sensor that is placed under the skin in the belly or arm. This sensor measures the glucose content of the fluid under the skin (and not from the blood) every 5 to 15 minutes. Depending on the model of the sensor, it will have to be replaced periodically, starting from 1 to 2 weeks or in some cases in 3 months. The glucose measurements can be accessed and tracked using an app or computer.

In different smaller studies, the continuous glucose monitoring system has been shown to better manage diabetes compared to using a skin-prick test alone. The way to know if the monitoring system is working properly is to check the number of events of the patient having a lower glucose value than normal between different cases. This is because if the number of incidences of below-normal glucose levels is higher than on average, it can seem like it has helped manage glucose levels better. In these studies, the low glucose incidences did not increase with the use of the continuous measuring system. While there are indications that this continuous monitoring can also help against developing long-term complications of diabetes, further research and large-scale studies are required to understand the relationship better and confirm all these results.

Advantages and Disadvantages of the Different Monitoring Systems

The main difference between the testing methods is detecting glucose from the blood (HbA1C and skin-prick blood testing) or from the fluid between the body’s cells under the skin (continuous glucose monitoring). The glucose digested first enters the blood before reaching the space between the cells. Therefore, the blood tests show more accurate levels of momentary glucose reading compared to the continuous monitoring device. So, it is highly recommended to use the at-home glucose monitor (skin-prick test) to confirm abnormal readings obtained from the continuous monitoring device before treating it.

In contrast, in some patients, identifying the trends of direction and speed of glucose change is more important to provide a proper treatment plan. In this case, the continuous monitoring device provides better information than the blood test method.

At a practical level, the continuous monitoring system does not require pricking or drawing blood for each measurement and can also take more measurements over time. However, inserting the sensor and replacing it requires going to a professional, and the system is more expensive.

What Are the Issues with Glucose Monitoring in Dialysis Patients?

Chronic kidney disease patients at the latter stages require dialysis. These patients are also highly susceptible to developing comorbidities, especially diabetes. This is because insulin secretion, sensitivity, clearance, and glucose metabolism are highly affected. Therefore, monitoring glucose levels in chronic kidney disease is essential. The process of dialysis in chronic kidney disease patients reduces the lifespan of the red blood cells. Additionally, the use of agents to stimulate the production of red blood cells causes there to be more time periods with less glycated hemoglobin. So, using blood for measuring glucose levels can be inaccurate in dialysis patients. Therefore, Kidney Disease: Improving Global Outcomes (KDIGO) has recommended the use of continuous glucose monitoring instead of measuring glycated hemoglobin to track glucose levels in patients undergoing dialysis.

This report has provided guidelines for time ranges of specific glucose values that a patient with chronic kidney disease should aim to achieve. The ideal situation is to have the following glucose levels:

• Greater than 12 hours per day in the target range of 3.9 to 10.0 mmol/L.
• Less than 15 min per day below 3.9 mmol/L.
• Less than 12 hours per day at 10.0 mmol/L.
• Less than 2 hours and 24 mins per day above 13.9 mmol/L.

Continuous Glucose Monitoring in Dialysis Patients

Preliminary studies indicate that controlling glucose levels based on data from continuous glucose monitoring is correlated with lower mean glucose levels at the end of the study. Larger-scale studies of these need to be conducted to confirm these results.

It must be noted that none of the continuous glucose sensing monitors are approved for dialysis patients because they have not been tested for this particular use. It is important to talk to the doctor and associated medical team to determine the best monitor to use and all the practical implications involved in using a continuous glucose monitoring system in chronic kidney disease patients undergoing dialysis.

Note: Some of the authors of the paper declared that they have relationships with companies that may provide treatment or diagnostic equipment relevant for described medical conditions. It is normal for authors to declare this in case it might be perceived as a conflict of interest. More detail can be found in the Conflict of Interest Statement by visiting the original article page.