Allergic reaction to medication

Do you control your diet and the amount of carbs you eat, or just rely on medication?
My body doesn't react well to meds so I rely on diet alone which with a little effort works very well for me.

I think that if you have a skin rash to one gliptin, then you will probably get the same with all members of the class.
I guess you have tried metformin and modified release metformin?
Something from the empagliflozin class would be my next suggestion, particularly empagliflozin, since it helps to lose weight and avoid heart attacks and strokes.
Then it gets fiddly.
Sulphonylureas increase weight and cause hypos with no effect on vascular disease.
Pioglitazone decreases risk of dementia and heart attacks etc without hypos, but puts on the weight.
Acarbose has awful flatulence and very few folk can take it.
Then there are the prandial glucose regulators, nateglanide and repaglinide, which have low but not zero risk of hypos; one takes them with each meal, so are useful for folk with variable eating patterns.
Then it is injections eg GLP-1, when one would want something ending -glutide which prevents strokes and heart attacks rather than one ending -enetide, which does not.
best wishes

Fruit and 'whole foods' can be high in carbs for the amount eaten.
I found that if I ate a carb dense food it would cause a spike which persisted, so all my levels were elevated for a day or so.
When I settled on foods which are ten percent carbs or less then my levels began to fall even though, if anything, I ate more.
Of course I can't promise that the same thing would happen for everyone, but it might help as the medication can't.
I had itching all over with the tablets I was given - horrible experience.