Evaluation of three potential screening tests for diabetes mellitus in a biethnic population.

We tested the ability of three potential screening tests for diabetes (fasting plasma glucose value greater than or equal to 140 mg/dl, 1-h postglucose (PG) load value greater than or equal to 200 mg/dl, and 2-h PG value greater than or equal to 200 mg/dl) to detect non-insulin-dependent diabetes in 130 diabetic Mexican Americans (MAs) and 50 diabetic Anglo Americans (AA) using the National Diabetes Data Group criteria as the standard. The sensitivity of the fasting plasma glucose (FPG) cutpoint in detecting diabetes was low in both AAs (36.0%) and MAs (59.3%) and was related to the age-adjusted prevalence rates of diabetes in the two ethnic groups (AAs, 4.9%; MAs, 10.9%). The 2-h PG load cutpoint had good sensitivity (greater than 93%) and specificity (greater than 99%) in both ethnic groups. The ethnic difference in the sensitivity of the FPG cutpoint appeared to be related to the greater hyperglycemia of diabetic MAs compared with diabetic AAs. Nearly 30% of diabetic MAs had FPG values greater than or equal to 200 mg/dl as contrasted with only 10% of diabetic AAs. The difference in severity of hyperglycemia between the ethnic groups appears to be unrelated to ethnic differences in adiposity, pharmacologic treatment, or delay in diagnosis, although longer disease duration in MAs may explain part of the difference.