Criteria for diagnosis of diabetes (as stated in the ADA Clinical Practice Recommendations.)
1) Fasting (no caloric intake for at least 8hrs) plasma glucose from 126 and above.
2) Casual (any time of day) plasma glucose of 200 and above and symptoms of hyperglycemia (high blood sugar)
3) 2hr plasma glucose level at and over 200 in the 75g oral glucose tolerance test.
There are some finer points regarding the criteria above, but that will be confusing to you, so go by the above.
Now, it's a known fact that with gastroplasty/gasterectomy (in other words, any surgery that makes your stomach smaller than its original size, be it for cancer, repetitve/refreactory ulcers or weight loss surgery) one of the secondary effects is temporarily raised blood sugar (higher than with normal stomachs) early after eating. Not sure if your surgeons explain this to you, but it's in medical textbooks, and we were taught this in med school. The quick rise takes place because food doesn't stay for 2-3 hours as in the regular stomach, so is passed through, and the sugars absorbed without delay. So long as it doesn't go up above the 200 level, and you don't have symtoms like abnormal thirst, fequent visits to the bathroom, or unexplained weight loss (

) no need to worry.