Never had that type of trouble with Metformin The worst was bloating real bloating as soon as I got rid of the wind everything was fine but the amounts and pressure of the gas stream lifted the bed sheets .
I Now take the new slow acting Metformin and tolerate that better . We in UK are always told to carry our BG meters with us and also a small Bottle of "energy drink" Lucozade and take that if you have a hypo . Carbohydrates in other forms tend to take longer to work hence your 2 hour nap