First off, you whould NEVER take a blood sugar reading any sooner that TWO HOURS after eating. It take that long for the food to enter your system and for insulin (either from your body or by injection) to work.
But 272 is still quite a bit high, even for 90 minutes after a meal. By 90 minute you should be below 200, like 180 or so.
This shows that you do NOT have control of your diet. You are STILL consuming too many carbohydrates --- breads, crackers, pastas, rice, corn, potatoes, etc. There are even some vegetable ( thought, by "common sense", to be healthy for you) that are high in carbs.
In addition to eliminating sugar from your diet, you ALSO need to REDUCE the amount of starches (carbohydrates) you eat.
it sounds like you need the advice of a nutritionist. First, keep a log book of EVERYTHING you eat. Here is a "typical" diet:
Breakfast: 1 cup corn flakes, artifical sweetner, 1 cup 2% milk, coffee with artificial sweetner
Lunch: Chicken breast sandwich, small order of fries, diet coke
Dinner: Beef Manhattan, mashed potatoes with gravy, green beans, diet chocolate pudding, iced tea no sweetner
Snack: Two ounces of potatoes chips, diet coke
Well, with this diet you have obviously tried to cut back the sugar. Good Job
But the carbs.....?
Breakfast: Corn flakes are naturally bitter, and so contain an additional helping of sugar. Substitue Cheerios with artificial sweetner.
Lunch: Chicken breast SANDWICH has TWO slices of bread. Have the chicken sandwich, but throw away the top of the bun. And french fries?!?! I oughta slap you...... :-)
Dinner: Beef Manhattan includes a slice of bread. That's fine, but refuse the mashed potatoes -- all starch. And gravy uses starch (either flour or corn stach) as a thickener.
Snack: POTATO chips??? Two ounces of Cheezits are better.
Note that you have had THREE servings of potatoes in ONE DAY. That is DEFINITELY too much starch!
Anyway . . . . make the log book, AND include your blood sugar reading (dates and times).
take the log book with you to the doctor AND to the nutritionist (ask you doctor for a referral.
SLIGHT changes in your diet and more attention to cutting carbs, should bring you into normal within a couple of weeks.
AND take those readings at the correct times! NO SOONER than two hour after eating. Preferrably, JUST BEFORE (like 5 minutes before) eating.