If someone had undiagnosed diabetes would there h1ac levels be high or low ?

Elevated A1C: Someone who has a new diagnosis of Diabetes is likely to have an elevated A1C level. Other screening tests include a Fasting Blood Sugar, a 2 hour Post Prandial blood sugar, or a Glucose Tolerance Test. The A1C looks at an approx. time period of 90 days, and represents the highest blood sugar during that 90 day period.

High: HA1C goes up and down with rising and falling Glucose levels respectively. So it is an indirect means of checking for persistently high blood sugar values.