What is one characteristic of high-risk gestational diabetes mellitus (GDM)?

The characteristic of high-risk gestational diabetes mellitus (GDM) is associated with obesity or being over the age of 35 years. These factors are significant because they contribute to the development of insulin resistance and increased glucose levels during pregnancy.

Obesity can lead to metabolic changes that make it more difficult for the body to manage blood sugar levels, while advanced maternal age is associated with the risk of various complications, including the likelihood of developing GDM. Thus, when a mother presents with obesity or is over the age of 35, she falls into a higher risk category for gestational diabetes, prompting closer monitoring and management during her pregnancy.

The other options do not align with high-risk characteristics for GDM, as being under 25 years of age or having a history of normal glucose tolerance would typically be associated with a lower risk for developing the condition. Low blood pressure is not relevant in the context of identifying risk factors for gestational diabetes.