Why Drug Combinations Are Used to Treat Type 2 Diabetes

You may also need to take insulin
Daytime activity can increase the body's sensitivity to insulin, so an oral drug, such as metformin, may control the fasting blood sugar. But since people are sedentary at night, they may need long-lasting insulin shot before bedtime.

"That will carry them into the next day," Dr. Trence said.

In time, they may also need a short-acting insulin, which is taken just before eating, to control blood sugar after meals.

Patients estimate the amount of insulin they need based on their exercise, calorie and carbohydrate consumption, and their blood-sugar readings, said Glenn Cunningham, MD, an endocrinologist and professor at Baylor College of Medicine in Houston.

You may not need to take medication forever
The primary challenges are making sure the blood sugar doesn't get too low from all the medications, a condition known as hypoglycemia, as well as preventing weight gain. There's more risk with certain drugs (such as insulin and sulfonylureas), than others. However, uncontrolled diabetes can lead to coronary heart disease, kidney failure, blindness, limb amputations, and premature death.

"We have to remember the cost of not doing the job," said Daniel Einhorn, MD, an endocrinologist and medical director of the Scripps Whittier Institute for Diabetes in La Jolla, Calif.

People who shed excess weight may—or may not—be able to come off their diabetes treatment. Genetics plays a role, as well as how far the disease has progressed. If a person has more vulnerable beta cells—the cells that make insulin in the pancreas—they'll need more medication, regardless of weight loss.