Here's the thing.
You lose the most body heat throught two, well three places.
Those are your ears, feet, and the fingers.
If you wear a t-shirt, gloves, and a hat, you are keeping everything warm that is needed (I am assuming that you are going to run with socks).
The hat will keep your ears warm-which is probably the most critical part to keep warm.
Besides, running a 10K, you will most likely not even need to finish with the hat and gloves.
I ran a cross country 5K race in 45 degree weather, and I was fine with light gloves and a shirt.
But then again, 30 degrees is a little colder than 45.
Goodluck!