By Marwan Hamaty, MD

Question: How can the summer heat affect diabetes control? Heat, especially extreme heat, is hard for anyone to tolerate. It’s especially hard on people with diabetes. When your body is exposed to heat, you lose more water through sweat, which can dehydrate you. Dehydration increases blood sugar levels. High blood sugar will make you urinate more often, which can dehydrate you even more. To stay hydrated, drink more fluids. You can tell when you’re drinking enough because your urine will be lighter-colored.

Heat can affect the way your body absorbs insulin. In hot weather, more blood flows to your skin. When you’re dehydrated, the opposite happens — less blood flows to the skin. Most types of insulin, especially short-acting insulin, don’t work as well when blood flow is decreased.

Diabetes won’t slow you down.

The heat can affect your medicines. If you leave insulin in a hot car, it will start to degrade. Bring along a cooler to keep insulin at room temperature or below. Heat can also damage test strips, leading to false readings. That’s going to affect your blood sugar management and how much insulin you take.

Be careful when you exercise in the heat. Watch for both high and low blood sugar. Your blood sugar can drop if you are on a medication that could cause low blood sugar. Being outside in hot weather and exercising produce similar symptoms, such as sweating and a fast heart rate, so it’s easy to overlook the early symptoms of low blood sugar. That’s why you need to check your blood sugar every hour or two while you exercise. Bring juice, glucose tablets, or glucose gel along for your workout, in case your blood sugar dips. If you take insulin, ask your [doctor] how to adjust your dosage when exercising.

Avoid sunburn. It damages your skin and can affect diabetes control. A serious sunburn causes inflammation, which in turn raises blood sugar. Apply a broad-spectrum sunscreen, and wear protective clothing and a wide-brimmed hat whenever you go outside.

Finally, take care of your feet. Avoid walking barefoot, especially if you have nerve damage that reduces your ability to feel sharp objects and hot surfaces. You might hurt yourself and not realize it. Wear protective shoes. Check your feet every day for cuts and other injuries. Also look for a scaly rash on your feet and white spots between your toes, which could be athlete’s foot. Sweaty feet make you more likely to get athlete’s foot and other fungal infections. Keep your feet dry, and treat athlete’s foot as soon as you see it with an over-the-counter antifungal cream.