"Should I be concerned?"
Yes, I would be. You need to see a doctor to ensure other health factors are not causing your hypoglycemia; thyroid disorder disrupting pancreas insulin production, poor pancreas functionality, kidney and liver disease, etc. Also, drinking liquor before eating.
A level of 55 mg/dl is not dangerously low but low enough to cause concern. Dipping lower could cause irreparable harm such as coma. Get an A1c test too to see how well you have managed your blood sugars. Good luck -
Agree with waverider about checking up on the low and possible causes. However, the 91 3 hours after eating is excellent! You want the level by 3 hours to be close to normal fasting levels.
Thank you for your input.
Perhaps more attention on nutrition valued food will help reduce fluctuation. Eating oats with milk [no sugar, honey and jaggery added] for breakfast and perhaps some fruits. For dinner light soup with clear veg / chicken stock and some bread with again some light fruit would help maintaining extreme fluctuation.
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