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Keep your cool when the sun’s out


veryone’s diabetes is different, and the effect of hot weather on blood glucose levels is a great example of that. Some people find a heatwave makes no difference to their control; others experience frustrating highs or lows when all they want to do is enjoy the sunshine. So why can this happen, and what can you do about it? Here are 10 tips that might help understand why blood glucose levels can rise or fall in the heat and what to do about it:

Unexpected hypo?

  1. When it’s hot you may be eating less than usual without realising it, so taking the same amount of insulin may cause a hypo.
  2. Activity, whether you’re exercising outdoors or just going through your day, can be more strenuous in hot weather, increasing your risk of a hypo. Testing your blood glucose even more frequently when you’re active can help you track how you are responding to the activity.
  3. Insulin is absorbed more rapidly into the injection site in hot weather, so your blood glucose may fall faster than you expect.1
  4. If your unexpected hypos on hot days are becoming more frequent you might be considering adjusting your insulin doses. Remember the FreeStyle Optium Neo meter has a trend feature to spot any patterns in hypos. Together with your blood glucose readings, you’ll have all the data you need to discuss your regimen with your diabetes care team.

Blood glucose high for no reason?

  1. Long periods of inactivity in the sun (such as lying by the pool) can raise your blood glucose in the short term.1 Your FreeStyle Optium Neo meter makes it easy to check your level in bright sunlight, as it has a paper-like screen with no glare. But don’t leave your meter or test strips in direct sunshine as they may give inaccurate readings if they get extremely hot.
  2. Dehydration and high blood glucose go hand in hand; if your blood glucose level is too high, you are more at risk of dehydration, and the more dehydrated you become, the more your blood glucose will go up.2
  3. Diabetic ketoacidosis (DKA) is also a risk if you become severely dehydrated, for example because you have vomiting and diarrhoea.3 Your FreeStyle Optium Neo meter has a built-in ketone testing feature, so you can easily check for ketones if you are worried.
  4. The symptoms of heat exhaustion (sweating, fatigue, nausea, dizziness) can be similar to a hypo so if you mistakenly take on glucose to treat it, your blood sugar level will rise.1 Testing your blood glucose can help you see whether you are really low, or need to cool down.
  5. Using insulin that’s been damaged by heat can cause your blood glucose to stay high as the insulin is less effective. Keep your supplies cool (but not frozen) and throw away any insulin that looks cloudy, granulated or brown.1
  6. Sunburn can cause your blood glucose to rise temporarily as the immune system responds to the injury to your skin.2 Sun cream is essential of course, and it’s handy that FreeStyle Optium test strips are individually foil wrapped – no need to worry about any spillages contaminating the whole batch.

Over to you

Do you find hot weather affects your diabetes control, and if so how do you handle it? Please share your tips on our Facebook page!



1. https://www.diabetes.org.uk/About_us/News_Landing_Page/Hot-weather-and-diabetes/

2. American Diabetes Association: Living with diabetes. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/factors-affecting-blood-glucose.html

3. /managing-and-monitoring/ketone-testing


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Modal libre bg * Scanning the sensor to obtain glucose values does not require lancets ×
*1. Scanning the sensor to obtain glucose values does not require lancets 2. A finger prick test using a blood glucose meter is required during times of rapidly changing glucose levels when interstitial fluid glucose levels may not accurately reflect blood glucose levels, or if hypoglycemia or impending hypoglycemia is reported but the symptoms do not match the system readings. ×

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