Summer and type 1 diabetes: how does the heat affect my diabetes?

Research is still needed to precisely understand how summer and temperature changes affect blood sugar levels and its management, here is what is known. 

The season has many variables that can affect either your blood sugar directly, how your body responds to external factors, or your insulin or diabetes gadgets like pumps.

Effects on blood sugar

It is suspected that the heat causes the body’s blood vessels to dilate which can increase the speed at which insulin is absorbed and potentially lead to hypoglycemia. This effect can be further emphasized if physical activity is done on a hot day, including leisure activities. 

Additionally, summer activities usually include being out in the sun for extended periods of time thus increasing the risk of getting a sunburn. A sunburn is considered a stressor to the body which  can raise blood sugar levels. It is therefore recommended to stay in the shade as much as possible and use a broad-spectrum sunscreen.

Risk of dehydration

Normally, when excess sugar is found in the blood, it will be excreted through urine. If the body has to produce a lot of urine, this will increase the risk of dehydration. Additionally, hotter times also increase the risk of dehydration making people who live with diabetes particularly at risk of dehydration during summer months. Hence the importance of keeping hydrated.

Additionally, one has to be careful when it is hot and humid. Normally, the body can cool itself by sweating, the sweat then evaporates to provide a cooling effect. However, if it’s humid, the sweat evaporates very slowly and becomes very ineffective in serving its purpose. Which is usually noticeable when comparing humid and drier climates, the more humid it is the more exaggerated the heat feels. 

Insulin and gadget troubles

If insulin is exposed to extreme temperatures it can become ineffective. Most types of unopened insulin should be stored in the refrigerator (between 2° and 8° C) and opened insulin can be kept at room temperature (between 13° and 26° C) .

A too high temperature or a direct and prolonged sunlight and heat exposure will change the composition of the insulin as it speeds up the breaking of its molecular structure rendering it less effective. So, for example, make sure not to expose your insulin pump to direct sunlight or leave your insulin pen in the car.

The heat can also alter the effectiveness of supplies such as test strips and meters. Be sure to check the manufacturer’s recommendations.


  1. Kenny, G. P., Sigal, R. J., & McGinn, R. (2016). Body temperature regulation in diabetes. Temperature (Austin, Tex.), 3(1), 119–145. doi:10.1080/23328940.2015.1131506
  2. Vimalavathini, R., & Gitanjali, B. (2009). Effect of temperature on the potency & pharmacological action of insulin. The Indian Journal of Medical Research, 130(2), 166-9.
  3. Managing Diabetes in the Heat | Features | CDC. (2018, July 12). Retrieved July 8, 2019, from https://www.cdc.gov/features/diabetesheattravel/index.html

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