TUESDAY, June 17 (HealthDay News) -- The diabetes drug metformin slows the onset of early puberty and reduces the risk of insulin resistance in girls at risk for both conditions, a Spanish study concludes.

"The findings indicate that we can slow down puberty. This is important, because when puberty is faster in girls, the appearance of menses occurs earlier, and this sequence of events may ultimately result in a shorter adult height," senior author Dr. Lourdes Ibanez, of the University of Barcelona, said in a prepared statement.

In addition, getting a first menstrual period before age 12 has been linked to an increased risk of breast cancer, and early puberty is a known risk factor for polycystic ovary syndrome, a common cause of infertility.

The study included 38 girls who had not yet reached puberty but developed pubic hair before the age of 8, which typically means they'll start puberty earlier than their peers. The girls in the study had another risk factor for early puberty: They'd been born small and experienced rapid catch-up growth during infancy, leading to increased belly fat. That put them at increased risk for insulin resistance, a risk factor for type 2 diabetes, according to background information in the study.

The girls were about 8 years old when they were enrolled in the study. They were divided into two groups of 19 - one that received no treatment , and one that received treatment with low-dose metformin once a day for four years.

Compared to the girls who received no treatment, the girls in the treatment group started puberty and menstruation later, gained about 50 percent less fat, and became less insulin resistant. The girls in the treatment group continued to grow taller, while most of the girls in the untreated group had already stopped growing.

The study was presented June 16 at the Endocrine Society's annual meeting, in San Francisco.