Yeast infections happen. They’re itchy, icky, and uncomfortable. At least they're usually easy to treat, either with a course of over-the-counter cream or prescription medication (or these highly effective yeast infection solutions). But what if they keep coming back?

“Yeast infections, or candidiasis, are incredibly common: More than half of women will have at least one in their lifetime,” says Katharine O'Connell White, MD, director of fellowship in family planning at Boston Medical Center. But there's a big difference between getting that gross cottage cheese-like discharge occasionally and having to run to the drugstore (or your doctor's office) several times a year.

If you're in the chronic camp, there's a chance that your yeast infections could be a sign of something more serious. One possibility: diabetes. Candida albicans, the fungus responsible for a yeast infection, normally lives in the vagina in small amounts. It typically won't hurt you, but it flourishes when there's excess sugar available, says Anita Somani, MD, an ob-gyn at Comprehensive Women’s Care in Columbus, Ohio.

If you have undiagnosed (and untreated) diabetes—or if you know you have diabetes but it's poorly-controlled—your vaginal secretions are likely to contain excess sugar. And when yeast in your vagina has access to that sugar, the yeast begins to take over and cause an infection, Somani explains.

Chances are frequent yeast infections won't be your only sign of diabetes; you might also feel extra thirsty, more tired than usual, or have blurry vision. But when in doubt, ask your doctor for a blood test to check your glucose levels—especially if other vaginal infections like bacterial vaginosis (bv) and STDs have already been ruled out.

If a patient comes to White with a recurrent yeast infection, her first step is to consider what she calls “yeast look-alikes," which include bv, trichomonas, chlamydia, and gonorrhea. (Here are 5 common reasons for vaginal itching other than a yeast infection—and 5 products that help.) Yeast infections can also sometimes be a sign of HIV: The body is weakened by the virus, which in turn allows yeast to increase and infect the vaginal membranes, Somani says.

Bottom line: If the itchy infection doesn't go away or keeps coming back, call your doctor and get it sorted out.