Teen Mom Mackenzie McKee Rushed to Hospital for Diabetic Spike

"Teen Mom 3" and "16 & Pregnant" star Mackenzie McKee is in the hospital for diabetic complications ... TMZ has learned.

Sources close to McKee tell us her mom and husband Josh rushed her to a hospital Wednesday night near their home in Miami, Oklahoma. We're told she was violently throwing up all night.

We're told Mackenzie discovered her blood sugar was "dangerously high" after testing with a home kit last night. They decided she needed to get to a hospital around 10 PM.

She is still there, and doctors are trying to stabilize Mackenzie's sugar levels.

Mackenzie has been training and dieting to compete in her next figure competition and that could have been a factor.

Mackenzie has had trouble controlling her blood sugar in the past ... she claims it caused a car accident last year.