I was able to control mine with diet (food choices) and exercise for about six years. I tested six times a day. Learned to eat fairly low carb and got a stationary bike that I got on for 8-15 min after every single meal. Sometimes my husband and I would walk for two miles or ride our real bikes for two miles. I used the stationary bike when the weather was bad. Wish I had room for one now. I started out with 8 min, then gradually had to add some as time went by, but I never rode it for over 15 min. I'm on insulin now. It's OK, just expensive when I hit the GAP or am in the deductibles at the beginning of every year.
Could be anything. Being sick can make it spike, added stress, pain from an injury, other medications, or your diabetes might be advancing.
When I was first diagnosed Metforin was enough. A year later even with diet and exercise it got worse so they added Glyburide. Then I was diagnosed bipolar and with it came meds that increased my sugar level so they increased my dosage.
Then last month they added insulin because my diabetes has gotten worse again. Then today thanks to steroids for a back problem my insulin was increased and doubled to twice a day.
Don't feel defeated because your meds change. Sometimes you have no control over it.