I am experiencing being tired after eating everyday is this a sign of diabetes or is it due to pms i got tested at my last blood test and it was negative but is it possible to have a false negative also my mom has type 1 diabetes am i at risk for it?

Some fatigue after eating a large meal can be perfectly normal as the circulation is diverted away from the brain& muscles to the intestinal tract for digestion. However if you eat a carbohydrate load, especially sweets, you may have swings in your blood sugar up&then down causing reactive hypoglycemia. An oral glucose tolerance test can be done to see your response to sugar. Check Hgb A1c also