Even though autumn is just around the corner, many places in the country still have a couple of hot spells left. And those surprise heat waves can be bad news for people with diabetes. It’s no secret that the elderly, the obese, and people with heart disease or respiratory conditions are vulnerable to heat-related illnesses. It’s less well known, however, that people with type 1 and type 2 diabetes are more likely than non-diabetics to suffer heat stroke, heat exhaustion, and heat cramps.

Impaired blood vessels

Diabetes can reduce the ability of blood vessels in the skin to expand (vasodilate), which in turn lowers the amount of blood that’s circulated under the skin’s surface to dissipate heat. In one study, the skin blood flow responses of non-diabetics were compared to those of age-matched people with type 1 and type 2 diabetes. During five minutes of heat exposure, vascular reactivity was decreased among those with diabetes. Another study showed that the internal temperature at which vasodilation took place during passive whole-body heat exposure was higher for people with type 2 diabetes than for others.

Sweating and diabetes

Sweating is an important cooling mechanism because heat is dissipated as sweat evaporates from the body. Poor glucose control and the presence of neuropathy, however, may affect the sweating response. In one study of people with type 2, sweat rates were reduced, especially in the limbs, both at rest and during exercise in the heat. According to the study, “The lower sweat rate was thought to be associated with diabetes-related peripheral neuropathy and autonomic dysfunction.”

Neuropathy also affects the sweat response in people with type 1 diabetes. In a study of patients with type 1, sweat responses to a heat stimulus (acetylcholine) were elevated when they were newly diagnosed, but decreased with “increasing duration of the disease during physical exposure to heat or exercise.”

These studies reveal that diabetes, along with health issues and advanced age, reduces the body’s ability to detect heat and impairs its capacity to respond to heat with adequate blood distribution and sweating. So if you have diabetes, be sure to take precautionary measures when the weather heats up.  

Source: Canadian Medical Association Journal