It's common. And most importantly, it's reversible. You can prevent or delay prediabetes from developing into type 2 diabetes with simple and proven lifestyle changes such as low glycemic & low carbohydrate diet, regular exercise.
Yes, normal value of blood sugar post eating is 120 - 140 mg/dl. Post meal value of 160 mg/dl indicates prediabetes.
Blood sugar of 140 to 199 mg/dL 2 hours post meals indicates prediabetes.