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10 Surprising Causes of Blood Sugar Fluctuations

Symptoms of low blood sugar are often uncomfortable to experience. Here’s how sleep, dehydration, stress, and even medication can affect your blood sugar levels.

by Elaine Francis, R.N.

Symptoms of low blood sugar, such as breaking out into a cold sweat, having shaky hands, or feeling your heartbeat quickening, can be uncomfortable to experience. But did you know that apart from what you eat, altered sleep patterns, dehydration, stress and a number of other everyday occurrences can cause fluctuations in your blood sugar?

What is Diabetes?

Diabetes mellitus is a condition where the body does not produce enough insulin, or where it does not respond to insulin in a normal way. Insulin is a hormone produced in the pancreas which acts to move sugar into cells to be used as energy. When our blood sugar becomes too low or too high, it can cause serious problems. Diabetes is a growing concern worldwide, and it contributes to the development of other serious illnesses like heart disease, stroke, and other vascular conditions.

People with type 1 diabetes typically have the condition from childhood or as a result of a problem with the pancreas developing later in life. It isn’t usually easy to predict who will have type 1 diabetes. The main way to treat type 1 diabetes is insulin injections paired with regular blood sugar monitoring.

People with type 2 diabetes may have more treatment options, ranging from simple diet management to taking tablets, using injectable non-insulin diabetes medications, and insulin injections. Some of the risk factors for developing type 2 diabetes include being overweight or obese, having a sedentary lifestyle, and carrying excess fat around the middle.

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Sometimes diabetes develops in pregnancy. This is known as gestational diabetes. The condition is associated with some risks to mother and baby, so needs to be closely managed. Gestational diabetes usually resolves after birth, but people who experience gestational diabetes seem to be at a higher risk of going on to develop type 2 diabetes later in life.

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How do I know if my blood sugar fluctuates?

We don’t know exactly how high or low our blood sugar is unless it is tested. This is usually done with a fingerprick test, where a drop of blood placed on a machine is analysed. Specialists may refer to these as capillary blood glucose – CBG. This can be done at home, and people who take insulin may have to check their blood sugar readings several times a day. Large fluctuations in blood sugar may cause symptoms like fatigue, confusion, dry mouth, headaches and blurred vision. Untreated critically out-of-range blood sugar levels can have extremely serious short and long-term effects.

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Why does blood sugar fluctuate?

Small fluctuations in blood sugar readings are normal, and blood sugar varies throughout the day and depending on activity, diet and a number of other factors. In non-diabetic people, these fluctuations are usually minimal, as sugar in the blood is carefully regulated by the body’s natural processes and insulin secretion. However, there are factors that contribute to bigger changes in our blood sugar levels:

1. Diet and fluid intake

A woman drinking water

Source: Unsplash

It shouldn’t come as much of a surprise to learn that the things you eat affect your blood sugars. It’s not just simple sugars, sweets and unhealthy desserts that can send blood sugar levels soaring. Some fruits are notorious for sending blood sugars out of range. Dried fruit in particular is a dense source of sugar. Fruits are still good for you as they are full of fibre and vitamins, so most people shouldn’t totally avoid them; just be mindful of the amount of sugar in some fruits.

Maintaining a healthy diet and weight is important for lots of reasons, and one of the most significant is reducing the risk of type 2 diabetes. In general, the more fat we carry, the less sensitive our body can become to the insulin we naturally release. Without having insulin controlling our blood sugar effectively, we can develop type 2 diabetes and be at higher risk for many serious health conditions.

Dehydration can also play a huge part in blood sugar control. Being dehydrated causes higher blood sugar levels, causing extreme thirst and, in the long-term, may affect the way in which the small blood vessels of the body work.

People who take insulin may follow a strict regime where they take a measured dose of short-acting insulin to match the carbohydrate content of a meal.

2. Artificial sweeteners

Soft drinks are an often overlooked route for lots of sugar to enter our diet. However, even sugar-free soft drinks, which may seem like a healthier option at first, seem to have a negative effect on our insulin sensitivity and blood sugar control too. Although artificial sweeteners don’t have the same kind of immediate blood sugar boosting effect that sugar has, regular consumption of artificial sweeteners affects the way we metabolise glucose.

Artificial sweeteners can be found in all sorts of food and drinks, but are most commonly found in soft drinks and yoghurts. Any sweet-tasting food that’s sold as ‘sugar-free’ or ‘diet’ is likely to contain artificial sweeteners.

3. Hormones

Some people find that their blood glucose levels fluctuate in line with their menstrual period, and diabetics may have to be mindful of this and adjust their treatment accordingly. Pregnancy is also a time when hormones and blood sugar levels are constantly fluctuating. Those who develop gestational diabetes need to be very closely monitored and managed to prevent any complications.

Those having hormone treatment may also find that their blood sugars are affected. If this is likely to be the case, the doctor prescribing the treatment should be able to give some advice. Some hormone treatments might actually help to regulate blood sugars.

4. Medications

Pill box with medicine

Source: Unsplash

Many medications have side effects, and some can actually affect our blood sugar levels. Steroids like prednisolone, often taken for inflammatory or autoimmune conditions, or exacerbations of certain lung diseases, are particularly well known for causing blood sugars to rise. People who take high doses of these kinds of steroids may need to have their blood sugar levels checked regularly.

Plus, medications given for diabetes – metformin, gliclazide and more – have an effect on blood sugar. Some work by improving the way our body makes and uses insulin, while others change the way our liver releases sugar into the blood. Certain medications are designed to have a long-term effect on diabetes management, whereas others have a more immediate effect on blood sugars. Sometimes it takes a little time and experimentation for doctors to get the doses and timings of diabetic medications exactly right for each patient.

5. Poor sleep

Source: Freepik

Poor sleep and unstable sleep patterns can have an effect on blood sugar levels. Our bodies naturally try and regulate blood sugars and insulin release according to our circadian rhythm – the natural pattern of wakefulness and sleep. Diabetics who work varying shift patterns, or night shifts, may find it particularly hard to stick to a healthy routine for blood sugar control. Anything that disturbs sleep – a new baby in the family, illness, or having to care for a loved one – can affect circadian rhythm and impact blood sugar control.

However, just as fluctuating sleep patterns can have an effect on our blood sugar, diabetics may find that having unstable blood sugars can cause a poor night’s sleep. Healthy bodies naturally regulate insulin and blood glucose overnight to maintain stable blood sugars, but people who are prone to unstable blood sugars may find that they wake up with out-of-range blood sugars. Timing meals, eating slow-release carbohydrates like wholegrain foods, and keeping a close eye on blood sugars around bedtime and first thing in the morning can help with maintaining blood sugar levels.

Diabetics and non-diabetics alike can find that bad night’s sleep can leave us feeling exhausted and run down. Even non-diabetics show more fluctuations in blood sugar when they’re sleep-deprived compared to when they’ve had a reasonable night’s sleep. This tiredness can also make us feel hungry, turning to sweet snacks to try and compensate for the low energy levels of fatigue.

6. Caffeine

A cup of coffee

Source: Unsplash

Caffeine has a significant effect on blood glucose management in type 2 diabetics, and may also contribute to the development of type 2 diabetes. Caffeine has long been a controversial factor in discussions of blood glucose control, and there have been some suggestions that some caffeinated drinks have some protective qualities. However, the most recent high-quality studies have found that there is a negative impact of caffeine on blood sugar management.

7. Stress

Stress – whether family and personal worries, pressures at work, injury, illness, or any of the myriad other stressors in our modern lives – has a complicated relationship with blood sugar control. But it is not just acute stress that can affect our blood sugar levels. Longer-term mental health conditions, anxiety and depression all have an impact on the way our bodies regulate insulin and blood sugar. The impact of this is most likely to be serious in diabetics but can affect anybody, diabetic or not. It has been suggested that longer-term, heightened stress levels keep the body in a low-key ‘fight or flight’ type state. What this means is that the nervous system is always ready to provide the body with more glucose. In fact, the correlation is likely to be complex and involve the impact of stress and mental illness on other aspects of life, including sleep, diet, activity, and use of alcohol and caffeine.

8. Exercise

5 seniors exercising together

Source: Active Health SG

When we exercise, we need extra energy in the form of glucose to be available to use in our cells. We also need insulin to enable those cells to retrieve and use the sugar from the blood that is circulating throughout our body. One immediate effect of exercise is to lower blood sugar, as we use up energy with activity. The length and intensity of a workout affect its impact on blood sugars. Diabetics, particularly those who use insulin, may be advised to check their blood sugar levels before and after a workout or any sustained intense activity. There is some evidence that exercising in the afternoon is of the most benefit to blood sugar levels, in keeping with the body’s circadian rhythm and natural energy level fluctuations.

In the long term, having an active lifestyle with plenty of healthy exercise may have a positive impact on blood sugar control, diabetes risk, and management of existing diabetes. Being active is one of the best things we can do to improve our overall health and reduce our risk of type 2 diabetes. Exercise is excellent for weight control, and we know that being overweight or obese is one of the highest predictors of type 2 diabetes. Regular, high-intensity exercise has both short and long-term benefits on blood sugars for non-diabetics, and significantly decreases the risk of developing type 2 diabetes.

9. Illness

Acute illness is closely associated with fluctuations in blood glucose levels. The physical stress of illness, the use of some medications, and the impact of illness on other aspects of life like sleep quality, hydration and nutrition all contribute to unstable blood sugars. It isn’t always possible to avoid an acute illness, but diabetics should be mindful of the potential effect of illness on their blood sugar control.

10. Alcohol

Alcohol is metabolised in a similar way to other simple sugars and usually causes an initial spike in blood sugar immediately after consumption. Unlike other sugars, alcohol affects the liver’s ability to deliver glucose into the bloodstream. This means that after an initial spike, blood sugars can dip significantly.

People with insulin-controlled diabetes mellitus are more likely to have hypoglycaemia – abnormally or dangerously low blood sugar levels – the morning after an evening of moderate to heavy alcohol intake. Alcohol is also a source of empty calories, which can contribute to weight gain for some people, increasing insulin resistance and the risk of type 2 diabetes.

How do I maintain healthy blood sugar levels?

Type 2 diabetes risk and management can respond well to lifestyle changes – diet, good amounts of exercise, and maintaining a healthy weight all go a long way towards preventing or reducing the impact of the condition. Managing our alcohol intake and being aware of hidden sugars in our diet – and the possible impact of artificial sweeteners – can also help.

Being aware of some of the more unexpected causes of blood sugar fluctuations is important to help us make healthy choices and to care for ourselves, and our loved ones, properly. It isn’t always possible to avoid stress, hormonal fluctuations, and acute illness, but just knowing the effect they might have can help us spot warning signs.

For those who struggle with their diabetes management, our specialised caregivers can help with blood glucose monitoring, providing medication reminders, assisting with insulin administration, and any other aspects of healthy lifestyle management.

Homage provides caregiving services for your loved ones at every stage. Our trained care professionals are able to provide companionship, nursing care, night caregiving, home therapy and more, to keep your loved ones active and engaged. 

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About the Writer
Elaine Francis, R.N.
Elaine Francis is a registered nurse with 17 years’ experience in healthcare. She turned to writing to follow her passion for realistic medical communication. She loves translating medical jargon into accessible language for the people who need to understand it most. When she’s not writing or working on a busy cardiology unit, she spends her time telling her children to hurry up.
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