First, it is not “normal” to have spikes. Well, it’s “normal” for people with diabetes who aren’t adequately treating their condition. But it’s definitely not good for you. Sure, a number in the 300s or 400s once a month is livable. But daily numbers in that range? Something’s gotta change (for the better).
Sometimes type 2s who have very high A1Cs and bg numbers in the 300s need insulin immediately to get the bg numbers down. Sometimes then, with weight loss, an eating plan, and daily exercise, they can go off insulin (at least for a while) and stick with an oral med or two or three.
Bg numbers lower than 300 can sometimes be decreased by methods mentioned in other posts: moderating carbs, drinking water, exercising. But numbers over 300 are very difficult to bring down without medicine. Especially consistent 300s.
As long as people are able to maintain lifestyle changes and as long as their beta cells are still producing insulin, the low- or no-meds routine may work for many years. However, by the time of diagnosis, many type 2s have lost at least half of their insulin production. It continues to dwindle over time. So other orals meds and blood glucose-lower injectables (insulin is the best known, also Byetta) need to be introduced. Even if you eat no carbs, protein is still converted partially to glucose and can increase blood glucose.
Some people try to avoid the additional meds and concentrate on carb reduction. If this works for them, great. But low carb eating (under 130 gram total per day from carb sources) is not always possible or even necessary to achieve on-target control (and I mean control of bg, blood pressure, and blood lipids–all important factors for preventing, delaying, and minimizing complications).
Please discuss with your health care provider. Your numbers may be high enough that you need a bit more medicine to help you tighten control. Tight control in the first few years of type 2 diagnosis has long-range positive effects in helping avoid complications.
Those highs you describe are no fun and must mean you don’t feel so great. Some additional meds may help you achieve better numbers immediately. Which, in turn, makes it easier to make smart choices and actually feel physically OK. We’ll be rooting for you, even those of us who don’t favor the Cowboys.