Hiya, when I started on Metformin I used to be sick sometimes. Particularly if I had a bit of a sugar binge, its kind of the new normal I'm afraid....
If you are feeling a bit low why not try a piece of fruit instead of biscuits (in the bin I suggest) or fruit juice (just liquid sugar, very bad for you, the manufacturers would have you think its a health food ... its not! Down the sink I would suggest also). Strawberries, blueberries, blackberries all of the berries are fairly safe for diabetics in moderation. Even a plum is not so bad, would not really recommend peach, apple or orange - well at least not a whole one, maybe a quarter would be ok. Nuts are also good, walnuts, pecans, macadamia nuts, handy to keep in the cupboard.
Good luck!