Can taking a daily vitamin D supplement prevent diabetes? Which is better for lowering your risk of diabetes: lifestyle changes or just medication? Is diabetes harder to treat if you're under age 20?

Recent national studies funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) have shed some light on these questions. Christine Lee, M.D., M.S., who helps oversee diabetes research at NIDDK, explains what you should know.

Taking vitamin D fails to prevent type 2 diabetes in adults

Vitamin D helps your body absorb calcium, one of the main building blocks of bone. It may also play a role in your nerve, muscle, and immune systems. Some studies had reported that low levels of vitamin D were associated with a higher risk for diabetes. But a new national study of more than 2,400 adults at high risk for diabetes, funded by NIDDK, found no added protection from taking the vitamin in preventing type 2 diabetes.

Lifestyle changes are best for preventing type 2 diabetes

A landmark national NIDDK-sponsored trial, the Diabetes Prevention Program, found that making lifestyle changes to lose some weight and become more active does a better job of reducing the risk of type 2 diabetes for adults at high risk for the disease than just taking the medication metformin.

Type 2 diabetes is increasing, especially among young adults of minority racial and ethnic groups. 

Compared with study participants who took a placebo (a pill without medicine), the lifestyle group reduced their risk by nearly 60%, while those taking metformin reduced their risk by only 30%. Adults age 60 and older saw even greater benefit, a 71% drop in risk. More recently, the study found that the adults who made lifestyle changes lost more weight in the short term, although taking metformin seemed to help patients who had lost at least 5% of their weight to maintain that loss over the long term.

Researchers are now looking at whether continuing metformin might help prevent cancer or heart disease in those at risk for diabetes.

Type 2 diabetes is more aggressive in youths than in adults

NIDDK has focused many efforts on understanding type 2 diabetes among youth. The result: several major studies of young people that found that the disease is very different in young people than in adults.

Among the findings were that type 2 diabetes is increasing, especially among young adults of minority racial and ethnic groups. Type 2 diabetes progresses faster in young people than in adults and also results in a high rate of diabetes complications. Additionally, metformin, the most common diabetes medication for adults, fails to keep type 2 diabetes from progressing in young people and fails to help achieve good blood sugar control in approximately 50% of youngsters, especially among African American youths.

But there is some good news.

A 2019 NIDDK study showed that gastric bypass surgery, although riskier, is more effective at reversing type 2 diabetes in teens with severe obesity compared with adults. And the U.S. Food and Drug Administration recently approved a new diabetes drug called liraglutide for young people over the age of 10. More research is needed to find good ways to prevent and treat type 2 diabetes in youths.