Final answer:
Caucasian race is not a risk factor for diabetes mellitus type 2, while a Body Mass Index (BMI) greater than 25, a history of gestational diabetes, and a history of polycystic ovary syndrome (PCOS) are known risk factors.
Step-by-step explanation:
The risk factor for diabetes mellitus type 2 that is not listed among the options given is Caucasian race. Other risk factors listed, such as a Body Mass Index (BMI) greater than 25, a history of gestational diabetes, and a history of polycystic ovary syndrome (PCOS), are all known to increase the risk of developing type 2 diabetes. Whereas obesity, particularly abdominal obesity, being overweight, having a sedentary lifestyle, consuming a diet high in sugars and fats, and having a history of metabolic conditions are all significant risk factors, race itself is a less specific risk factor with the incidence of Type 2 diabetes occurring in many demographic groups.