The level of glucose in the blood at any given point is an essential indicator of health and well-being. Most people know that higher blood sugar levels over time can cause health complications such as diabetes, while lower levels bring their own dangers in terms of limited energy. But another factor that comes into play is the degree to which the glucose level fluctuates over time and what that indicates.
Based on factors like food, exercise, mood and the time of day or sleep, blood sugar levels do tend to fluctuate through the day or between different days. The degree to which these levels change or vary over time is called glycemic variability. It is a metric that can be used to examine how the body processes glucose or a person’s overall health.
By looking at how glycemic variability is defined and measured and how it influences health, we can know what to do to improve glycemic control or know what warning signs to look out for.
- Glycemic variability (or glucose variability) is the fluctuation or change between blood sugar levels over the course of the day, and monitoring it can offer some important health insights,
- Glycemic variability is important because it can be an indicator of other health problems, and spikes or crashes can damage tissues,
- By monitoring glucose levels, adhering to a balanced routine, eating nutritiously and avoiding sugar spikes, GV can be controlled and reduced over time.
What is glycemic variability, and how is it calculated?
As mentioned above, glycemic variability (or glucose variability) is the fluctuation or change between blood sugar levels over the day or night. This variation occurs for everyone, but the degree to which these levels change can be different for different people and offer important health insights.
Glycemic variability (GV) is measured in terms of the difference in glucose values over time and thus requires monitoring of glucose at different periods. Although everyone has a rise or fall in blood glucose over the course of the day, based on the intake of food or other factors such as exercise, sleep, stress and so on, a high glycemic variability is still a cause for concern.
The most common method used to calculate variability is the standard deviation or SD. It is an indicator of how far from the average a person’s glucose values go over the course of a particular amount of time.
So, for instance, if someone has had blood glucose levels that are especially high or low over the course of the day, they will have a larger SD than someone whose measurements are within smaller intervals of their average. The SD is calculated relative to their own average glucose levels but also takes into account the average range below or above which an individual is considered to be having a ‘glycemic excursion’, which means the incidence of either hyperglycemia (high blood glucose) or hypoglycemia (low blood glucose).
Thus, GV acts as a continuous stream of information about changes in blood sugar levels, and the degree of standard deviation can provide data about how often an individual’s blood glucose goes significantly above or below the ideal recommended range.
Based on this data, GV can also sometimes be represented as a percentage or in terms of mg/dL variation, which is one of the common measures of the amount of glucose in the blood. Although there isn’t plenty of data on optimal glucose variability for people with no diabetic or prediabetic impairment, many studies suggest that lower GV is an indicator of a lower risk of certain problems.
The few studies that use continuous glucose monitoring in people without diagnosed metabolic dysfunction found that the average postprandial (post-meal) glucose peak was 90 to 110 mg/dL. A normal average for glucose excursions or GV for someone without any medical or metabolic conditions is between 24 to 28 mg/dL, but an obese person or someone who is pre-diabetic may have a value closer to 50 mg/dL. Keeping the GV under 12% is generally considered to be within the healthy range.
Using continuous glucose monitoring (CGM) is a way to find and measure glycemic variability through the day and can be useful for people who are trying to measure and control spikes or dips in glucose through the same.
Why does glycemic variability matter?
Glycemic variability is important because it is an indicator of blood glucose changes that can lead to other health problems. Studies have shown that large spikes or crashes in glucose levels (high GV) can damage tissues even more than elevated glucose levels do. High GV has been linked to various problems—in the immediate term, this could mean fatigue, depression and anxiety, while in the longer term, it can cause insulin resistance, metabolic dysfunction and cardiovascular disease.
Another factor to consider is that GV is not just an indicator of the fluctuation in blood glucose; it can also serve as a marker of oxidative stress. A heightened GV generally leads to or suggests greater oxidative stress in the body. Oxidative stress is an imbalance between antioxidants and free radicals—in essence, this means the body takes longer to repair cellular damage.
Oxidative stress is linked to ageing as well as a number of diseases in the long term, including cancer, hypertension, neurological or degenerative diseases and various others. Monitoring GV can be a way to keep track of oxidative stress, and reducing it can also be an important step in reducing oxidative stress. Over time, high levels of GV, which means sudden upswings or crashes in glucose levels, can lead to significant health problems.
GV is also important because it provides a different measure than simply standard blood sugar testing. Continuous monitoring of blood sugar can help better measure glycemic variability and be aware of factors that might contribute to it. Some of these include diet, exercise, stress or other health conditions that we need to be aware of.
Variability may be a warning sign even for people with ‘normal’ glucose levels. A study in 2018 found that nearly 80% of participants whose blood sugar levels were within the standard range experienced post-meal glucose spikes that were often close to the pre-diabetic range. However, a review of research around GV found that links to oxidative stress that were seen in animal studies have yet to be reproduced in real-life human studies.
Nonetheless, in diabetes patients, GV was an important indicator of increasing mean glucose values and chronic complications arising from type 1 and 2 diabetes. Moreover, studies have also found that a high glycemic variability is frequently a warning sign of metabolic dysfunction and increasing insulin resistance. Given that GV can indicate a variety of health problems, what are the factors contributing to it, and how can glycemic variability be reduced?
How to improve glycemic control?
Some factors contributing to GV are diet, exercise, sleep and stress levels. Controlling GV has been the focus of several studies, and below are some ways in which glycemic control can be improved.
Diet is the biggest contributor to blood glucose levels and consequently to GV. Foods that are high in sugar, refined sugars or carbohydrates cause a sudden spike in glucose, which then leads to greater insulin secretion. In the long term, this cycle increases GV and can also lead to metabolic problems.
Thus, one of the best ways to control GV is to stick to a diet that does not contain too many refined sugars and carbohydrates. Other strategies, such as pairing carbohydrates or sugars with protein and healthy fats, have also been shown to lower glucose spikes.
A diet high in fruits, vegetables, nuts, legumes, and whole grains can help reduce GV and oxidative stress in the body. Foods that are high in antioxidants (such as certain fruits, vegetables and nuts) and eating smaller portions to avoid sudden glucose spikes can also help control GV.
Some studies indicate that restricting carbohydrates at breakfast can improve glycemic variability, but others show that eating more carbohydrates in the first half of the day and then avoiding sugar or large meals later in the day can also reduce glycemic variability.
Exercise is another factor that can influence GV. Intense exercise can cause a sharp rise or fall in blood sugar, caused by glucose being released by the liver to fuel the muscles. Regular aerobic and anaerobic exercise has also been shown to reduce glucose variability in studies by improving insulin sensitivity. Other studies have also shown that non-exercise physical activities or low-intensity activities, like walking after meals, can improve glycemic control.
Obesity has been shown to be linked to high GV and subsequently to various related health problems. Thus, weight reduction and weight management can have an influence on reducing GV and improving glycemic control.
Studies have shown that being aware of GV and continuous glucose monitoring positively impact glycemic control in people with diabetes. However, in many cases, the results were also suboptimal because of poor self-reporting.
Various studies have shown links between factors such as sufficient sleep, stress levels and blood glucose. Getting ample sleep, maintaining low-stress levels, and regular hours can also help improve glycemic control.
Therefore, while being aware of GV is the first step in controlling blood sugar levels, factors such as a healthy diet, regular exercise and sufficient sleep can be key elements in maintaining stable glucose levels and lowering the variability.
Overall, GV needs to be monitored so one can understand if there are any warning signs regarding various diseases. High GV levels can also have a negative effect on overall health. By monitoring glucose levels, adhering to a balanced routine, eating nutritiously and avoiding sugar spikes, GV can be controlled and reduced over time. Factors such as exercise, sleep, stress levels, and weight can also be managed better in order to improve glycemic control.
Disclaimer:The contents of this article are for general information and educational purposes only. It neither provides any medical advice nor intends to substitute professional medical opinion on the treatment, diagnosis, prevention or alleviation of any disease, disorder or disability. Always consult with your doctor or qualified healthcare professional about your health condition and/or concerns and before undertaking a new health care regimen including making any dietary or lifestyle changes.