If my blood sugar is 160 two hours after eating dinner, could I be diabetic?

Not diabetic but. If your bs exceeds 200 then you may have diabetes, however, you can have possible pancreatic beta cell dysfunction if your carb load (60-70 grams) and bs fall within 140-199 at 2 hours post ingestion.
No. After regular meal, between 140-200 mg/dl indicates impaired glucose tolerance (prediabetes). If test results are in this range, a patient is at an increased risk for developing diabetes. Greater than 200 mg/dl indicates diabetes.