Hypoglycemia and constipation

They might have the same cause, without cause and effect. Metformin doesn't usually cause hypoglycaemia
According to something I read recently by John Yudkin, who was a VERY respected nutritionist in the late 1960s, cutting out sugar and white flour can help in psychological illness. It can also help in insulin resistance.
Worth a try?
as for constipation
remember to drink a lot of water every day and eat fibrous vegetables. If that's not enough to prevent another attack, try taking psyllium husks, which you can buy online or from health food shops.
See your doctor