Prediabetes: Epidemiology, diagnosis, and management

Table 1 Main advantages, disadvantages, and clinical uses of tests for prediabetes screening and diagnosis

Test	Advantages	Disadvantages	Main purpose
OGTT	Reference standard for diagnosing IGT; detects post-load dysglycemia[1,117]	Time-consuming; requires fasting and at least 2 h of testing; multiple blood samples; affected by recent diet, acute illness, stress, and medications	Diagnose IGT; assess glucose tolerance; clarify borderline or inconclusive cases
FPG	Simple, inexpensive, widely available; requires only one blood sample[1,117]	May miss isolated IGT or post-load hyperglycemia; affected by short-term physiological variation, acute illness, and stress	Diagnose IFG; initial screening in routine practice
HbA1c	No fasting or timed glucose loading required; reflects glycemic exposure over past 2-3 month; relatively low short-term variability[1,23,24]	Affected by altered red cell turnover, hemoglobin variants, anemia, blood loss, kidney disease, pregnancy, HIV, and some medications	Screening and diagnosis according to specific guidelines; risk stratification and follow-up monitoring
CGM	Provides continuous glucose profiles; captures glycemic variability and postprandial excursions; avoids repeated venipuncture[27,28]	High cost and limited access; sensor-related discomfort; interstitial glucose may lag behind blood glucose; diagnostic thresholds for prediabetes are not standardized[28]	Mainly used in diabetes management; may be useful for research or selected high-risk individuals, but not routine prediabetes diagnosis

OGTT: Oral glucose tolerance test; IGT: Impaired glucose tolerance; FPG: Fasting plasma glucose; IFG: Impaired fasting glucose; HbA1c: Glycated hemoglobin; CGM: Continuous glucose monitoring; HIV: Human immunodeficiency virus.