Does hot summer weather change how insulin works in my body?

Extreme temperatures, particularly intense summer heat, absolutely change the way your body processes insulin, and it can make managing your blood sugar very unpredictable.

When you are out in the hot sun, your body tries to cool itself down by expanding the blood vessels close to the surface of your skin. This process, called vasodilation, increases blood flow. If you have recently injected insulin, this increased blood flow causes the insulin to be absorbed into your bloodstream much faster than usual, often leading to sudden, unexpected low blood sugars.

Additionally, the heat itself can be deceiving. The physical symptoms of heat exhaustion—like heavy sweating, a rapid heartbeat, fatigue, and shakiness—are almost identical to the symptoms of severe hypoglycemia. It is very easy to mistake a dangerous low blood sugar for simply feeling too hot.

On the flip side, if you become dehydrated in the heat, your blood volume actually decreases. This concentrates the glucose in your blood, causing your numbers to spike high.

To stay safe during the summer, always keep your insulin out of direct sunlight (heat breaks down insulin proteins, making it ineffective), test your blood sugar much more frequently than usual, and drink plenty of water to prevent dehydration spikes!