[ADA criteria undervalues the impact of diabetes in a high-risk Spanish population].

OBJECTIVE: The main aim was to investigate the prevalence of abnormal glucose homeostasis (impaired fasting glucose, impaired glucose tolerance and undiagnosed diabetes) on high-risk Spanish population. The second, to determine the prevalence and usefulness of classical risk factors for diabetes screening according WHO and ADA criteria and to evaluate the potential effect of different stepwise strategies.

DESIGN AND SETTING: Cross-sectional, multicentric, selective screening study carried out in primary health care which involved 9 health care centres and 1 diabetes unit (230,000 inhabitants).

PATIENTS: Individuals aged > 40 years, non pregnant with at least one major risk factor for diabetes: BMI > or = 30 kg/m2, a first degree relative with diabetes, previous abnormality of glucose tolerance or the use of oral hyperglycaemic drugs for a long time.

MEASUREMENTS: Database including sex, age and risk factors. Diagnoses were based on measurement of fasting plasma glucose (FPG) followed by a 2h-plasma glucose (2hPG) using a 75 gr. oral glucose tolerance test (OGTT). Positive predictive value (PPV) and odds ratio were calculated for each risk factor. The FPG concentration which maximised the sensitivity and specificity with respect to the 2hPG was established by means of the ROC-curves (receiver operator characteristics).

MAIN RESULTS: 580 individuals were evaluated, 250 males (43.1%), mean age 58.1 +/- 10.7 years and BMI 31.2 +/- 5.2 kg/m2. A total of 132 (22.7%) individuals presented diabetes according the WHO criteria, 79 (13.6%) according ADA and only 53 (9.1%) according both sets of criteria. FPG > or = 126 mg/dl (7 mM) predicted a diabetic 2hPG with high specificity (94.2%) but a very low sensitivity (40.2%). If that cut-point was used alone for early screening half the diabetics with normal FPG but with a diabetic 2hPG would not have been diagnosed. According the WHO criteria PPV for classical risk factors oscillated between 23.4-29.1% and were significantly higher than those obtained according ADA criteria (11.6-18.3%; p < 0.01).

CONCLUSIONS: The OGTT is still the cornerstone for diabetes screening thus the FPG predictive value greatly decreases the 2hPG predictive value. ADA criteria undervalues the diabetes impact mainly on high-risk population.