Many people with diabetes will describe themselves as feeling tired, lethargic or fatigued at times.

It could be a result of stress, hard work or a lack of a decent night’s sleep but it could also be related to having too high or too low blood glucose levels.

Tiredness as a symptom of diabetes

Regular tiredness, particularly tiredness following meals, is a common symptom of diabetes.

What causes people with diabetes to be tired?

Two common reasons for tiredness or lethargy are having too high or too low blood sugar levels.

In both cases, the tiredness is the result of having an imbalance between one’s level of blood glucose and the amount or effectiveness of circulating insulin.

If you feel tired during the day, despite having slept well, it could be a result of either high or low sugar levels.

It is best to test your blood glucose levels to see whether the tiredness is indeed a result of having high or low sugar levels.

This is particularly important for people on insulin.

Tiredness and high blood sugar levels

Blood glucose levels go high when there is either insufficient insulin (typically in the case of type 1 diabetes ) or the insulin is not working effectively enough (typically in type 2 diabetes).

To provide us with energy, insulin is needed to transport glucose from blood into our cells to be used for energy.

When there is not enough insulin, or the insulin isn’t working effectively, it means the sugar in our blood cannot get into our cells and therefore our cells do not receive the energy they need. As a result, we feel tired.

Managing tiredness and high blood sugar after meals

If tiredness is accompanied by high blood glucose levels after meals, it can indicate one or more of the following:

  • The carbohydrate you are eating is too quick acting for you medication to cope with
  • You are eating too much carbohydrate for your medication/dosage
  • Your medication/dosage is not strong enough

You should only change your medication dosage if your doctor has approved you to.

Putting on weight is a common indication that one’s insulin levels are too high. People who are overweight and experiencing tiredness as a result of high blood glucose levels may be able to combat tiredness by reducing their carbohydrate intake.

A doctor or dietitian should be able to help you with how to reduce your blood glucose levels whilst achieving a healthy weight.

Tiredness and hypoglycemia (low blood glucose levels)

When blood glucose levels are low the body is in a similar position as a car that has run out of fuel; unless you are able to add more fuel, the car will quickly come to a juddering halt.

Similarly, when blood glucose levels are low, you need to take in more carbohydrate to provide your body with the energy your body needs.

If you are regularly experiencing low blood sugar levels, your dosage of medication may be too high.

For people on insulin, hypoglycemia can also occur if insulin is injected (or bolused) too soon before eating.

Tiredness upon waking

If tiredness occurs upon waking after a full night’s sleep, it can also be a result of too high or to low blood sugar levels overnight.

Tiredness accompanied by a headache in the morning can often be a sign of an overnight hypo in people taking insulin.

Managing morning tiredness

If you are regularly feeling tired in the morning, despite having had a full night’s sleep, it’s worth testing your blood sugar upon waking to see if your tiredness is related to your blood glucose

Some people may also wish to wake during the night to test their blood glucose levels to see if they’re experiencing high or low blood sugar overnight.

Blood sugar levels can fluctuate overnight and your doctor or diabetes specialist should be able to advise if your sugar levels are causing any problems.

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