I Have A Question About Linea Nigra. I Am Not

I have a question about linea nigra. I am not pregnant and never have been I am a 20 yr old female. I have heard that having it could be a sign of diabetes. Is this true? I have many other symptoms of diabetes yet have not been tested yet (yeast infections sky rocketin heart rate ocassionally. Slow healing cuts and bruises. Fatigue. Weight loss. Ect...) but I am just curious where the dark line on my belly came from and if it could be yet another symptom of diabetes. And if so is there a way for me to test to see if I might have diabetes at home before going to a doctor so I might have an idea?