Women with low levels of the hormone adiponectin were up to seven times as likely as others to develop the condition during pregnancy, the study found.
Adiponectin can protect the body against insulin resistance, inflammation and heart disease.
Researchers said a straightforward and cheap blood test for the hormone could spot women who face a higher risk before they conceive or in early pregnancy. They could then be treated to avoid potential complications.
The study was published in the journal Diabetes Care.
Gestational diabetes affects up to 5% of all pregnancies, and almost one in three of these women will go on to develop type 2 diabetes in their lifetime.
Researchers analysed data from blood samples from about 4,000 women during pregnancy between 1985 and 1996. There were 256 cases of gestational diabetes.
Women of a healthy weight with low adiponectin levels were 3.5 times as likely to develop the condition as other normal-weight women.
Overweight women with normal levels of the hormone nevertheless had a 1.7-fold risk of gestational diabetes than healthy weight women. But those with low adiponectin levels faced a 6.8 times greater risk.
Lead researcher Monique Hedderson PhD from the Kaiser Permanente Division of Research in Oakland, California said: 'Low adiponectin levels were linked with gestational diabetes even for women without traditional diabetes risk factors such as being overweight, so this could be an important clinical marker for women who may become pregnant.'
Researchers now want to investigate whether diet changes and exercise can increase adiponectin levels.