Searing heat that blankets much of the nation is particularly consequential for people with diabetes.

"They're more vulnerable to emergencies during heat waves," said Dr. Ashley Peterson, an osteopathic physician who practices at Dedicated Senior Medical Center in Columbia, South Carolina.

The Centers for Disease Control and Prevention warns people with both Type 1 and Type 2 diabetes are vulnerable to heat-related complications, because their bodies can't cool down as effectively. The higher temperatures can change how insulin is processed in the body and dehydration can lead to higher blood sugar levels.

"They can often have what we call peripheral nerve damage and reduce blood flow to their arms, their legs, their extremities," Peterson said. This could put diabetics at higher risk for infection, heat stroke and heart disease, she said.

Healthcare providers in Boston are using email alerts to warn patients of hot days and prompt them to take extra care, especially for people with chronic diseases.

Peterson recommends lots of water on hot days, especially humid ones because people with diabetes are more likely to suffer from urinary tract infections or cardiovascular or kidney disease.

Among other tips, she recommends making sure insulin is stored in cool temperatures. If traveling, she suggests keeping a cooler or ice chest on hand. And importantly, she says, maintain a relationship with a trusted primary care doctor or endocrinologist.