A Guide to Managing Diabetes in Hot Weather

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What You Need to Know

  1. In warmer conditions blood vessels can dilate making medication such as insulin more effective. Doses may have to be altered to avoid hypoglycaemia.
  2. As blood sugar levels fluctuate more in warm conditions, you should take readings more regularly to keep track of the glucose mmol/L (millimoles per litre) in your blood.
  3. High blood sugar and can help cause dehydration and vice versa, meaning it’s important to take on lots of fluids.
  4. Try to keep rigorous activities to cooler times of day.
  5. The symptoms of hypoglycaemia, which include sweating and fatigue, can be harder to spot in Summer.
  6. Sunlight can damage insulin. This can make it less effective, increasing the risk of hyperglycaemia.
  7. When protecting against sunburn, be especially careful with your feet. Diabetes can damage the nerves of the feet, reducing their ability to heal from abrasions, blisters and burns.

Hot weather, as welcome as it is, can pose certain challenges when it comes to managing diabetes. The effects of higher temperatures are not uniform for all diabetics, and whilst some might be more at risk of hypoglycaemia, others will find hyperglycaemia more of a concern. In addition, diabetics are usually more susceptible to heat related health problems that affect everyone, such as dehydration and heat exhaustion.

However, with the right preparation, there’s no reason you can’t safely enjoy the sun. Here we look at the things you’ll need to consider when managing your condition in warmer weather.


If you have high blood sugar your body will attempt to filter surplus glucose out through fluids. If we’ve not taken on sufficient fluids too allow the kidneys to filter out glucose through urine, the body will take water stored in our cells, leaving you dehydrated. In addition, Diabetes can cause damage to the sweat glands, making it harder for the body to cool itself and increasing your chances of overheating.

It’s important to keep hydrated. This can be done using water, or if appropriate for your glucose mmol/L, a sugary drink could be a useful way to replenish fluids and sugars at the same time. (You will need to keep regular tabs on your blood sugar, as it can fluctuate to a much great extent in the heat, which may require you to confer with your medical team and alter your normal regime.)

To avoid the possibility of dehydrating, make sure you have access to fluids and try and schedule any rigorous physical activities for cooler times of day.

As explained above, diabetes can affect the bodies ability to cool itself, meaning heat exhaustion is a greater risk. If not treated it can lead to heatstroke, where the body’s core temperature rises beyond the point it can self-regulate back to normal. This is considered to be a medical emergency.

If the following symptoms present, it could be heat exhaustion;

  • Sweating
  • Dizziness
  • Nausea
  • Cramps
  • Headaches
  • Increased heart rate

Immediately move into a cool shaded area, water and rest to avoid the possibility of heat stroke ensuing. If there is hyperventilating or loss of consciousness, call an ambulance.


Those who take insulin or another form of medication which works to lower blood sugar levels should be aware that such treatments can be considerably more potent in warmer temperatures. (Heat causes the blood vessels nearest to the surface of the skin to dilate and, as a result, insulin is absorbed into the body much quicker.)

It’s possible, therefore, that your usual dosage, rather than keeping your blood sugar levels within the normal range so as to prevent hyperglycemias, could actually bring you 4 mmol/L, thus triggering hypoglycaemia. This is compounded by the fact that the body’s metabolism works faster in hot weather (it can also encourage us to get out and be more active which will also have an affect).

This is especially problematic for a couple of reasons. Firstly, if you are taking your regular prescribed dosage, which after all has been taken to diminish the risk of blood sugar being too high, the onset of a hypo may catch you unawares. Secondly, even if you are used to occasionally experiencing hypos as a result of your medication, many of the symptoms of a hypo are fairly consistent with being hot and bothered, which can make them harder to spot in the height of summer. It’s therefore prudent to be extra vigilant when the following signs present themselves;

  • Sweating
  • Dizziness
  • Confusion
  • Aggression
  • Fatigue
  • Hunger

Be sure to keep emergency sources of glucose on you and, if you are experiencing lower blood sugar than normal, talk to your doctor about reducing your insulin intake.


As well as being wary of hypos, it should be remembered that hot weather can also make it harder to regulate the rise of blood sugar levels. One of the chief reasons for this is that, if you allow yourself to become dehydrated, the lack of water will cause the volume of your blood to fall. As a result, the concentration of glucose in your blood will be higher and could stray above 7 mmol/L.

This can create something of a vicious cycle, as one the ways the body attempts to jettison excess glucose is through urination. This will, in turn exacerbate your dehydration and increase your need for fluids.

Obviously, the balance of diet and exercise are vital to managing your blood sugar. Though it needs to be done in such a way that you won’t put yourself at risk, you shouldn’t stop exercising when it’s warmer, as inactivity can also mean you’ll be left with too much sugar in your blood.

You should also be aware that, whilst insulin works more effectively in the body in hot weather, if not stored properly it can be damaged by sunlight, making it less effective. This could leave you with undesirably high blood sugar. To avoid such problems, it’s important to keep your medicine and equipment safe from the heat…

Looking After Your Insulin and Equipment

Heat pumps can become loose in hot weather due to sweat compromising the adhesive, which may require you to apply products to the skin to resolve the issue. If you disconnect the pump, you need to be sure to remember to make up for missed doses. You can keep the pump in a pocket as opposed case or belt to avoid direct sunlight.

Your insulin itself should always be kept out of the sun and when taking supplies out with you. If you notice your insulin has changed colour or consistency in the heat, it could be dangerous to take it.

To ensure their accuracy, test strips also need to be kept out of the sun.

Avoid Sunburn

Whilst its always advisable to protect your skin from the sun, it can be especially important if you’re diabetic as your bodies reaction to the stress of burning can raise blood glucose. Be especially careful is you use sulphonylureas antidiabetics, as these can increase your sensitivity to sun.

Foot Care

Diabetes damages the nerves of the feet and, if they’re damaged, this can lead to a number of complications, not least of all foot ulcers which can be difficult to heal. Though you may find it difficult to notice problems as they develop due to reduced sensitivity in your feet, you need to check them frequently to ensure they’re in good shape.

Don’t be tempted to go bare foot as you’ll increase your chances of getting a burn or blister. Wear comfortable shoes and make sure you apply a generous amount of sun cream to any part of your feet that are left exposed.

Further Reading

  1. Read up on the science behind diabetes.

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