HI, thanks for using healthcare magic The blood sugar is elevated after the food is absorbed into the blood stream therefore affecting the level of sugar in the blood. This is the reason foods with a low glycemic index , meaning they are broken down slowly, cause a slower rise in blood sugars. If your foods is remaining in the stomach longer then it would be less likely to cause highs. The hernia can slow down digestion if it is large but this would not cause high readings after meal, it would cause the opposite because the food is not at the blood stream. A hernia can worsen reflux symptoms as well and therefore bloating, the use of medication would help. I hope this helps