Comparison of glycemic and IR assessment methods.
| Method | Purpose | Sample type | Time period reflected | Advantages | Limitations | Clinical use | Cost and accessibility |
|---|---|---|---|---|---|---|---|
| Fasting plasma glucose (FPG) | Diagnose hyperglycemia and screen for diabetes or impaired fasting glucose | Venous blood (fasting) | Single time point (basal glycemia) | Simple, inexpensive, widely available; standardized diagnostic thresholds | Does not capture postprandial excursions or glycemic variability; limited sensitivity for early dysglycemia; influenced by acute stress or illness | Initial screening and diagnosis of diabetes; routine metabolic assessment | Very low cost; universally accessible |
| Homeostasis model assessment of insulin resistance (HOMA-IR) | Estimate IR | Venous blood (fasting glucose + fasting insulin) | Single time point (fasting state) | Simple surrogate of IR; useful in epidemiological studies | Not validated for individual clinical decision-making; influenced by insulin assay variability; limited interpretability across populations | Research and population studies: an adjunct marker of IR | Low–moderate cost; insulin assays may limit availability |
| Glycated hemoglobin (HbA1c) | Assess long-term average glycemic exposure; diagnose and monitor diabetes | Venous blood | 8–12 weeks (integrated mean glycemia) | Well standardized; no fasting required; predictive of microvascular complications in diabetes | Does not reflect short-term glucose fluctuations, postprandial hyperglycemia, or hypoglycemia; similar HbA1c values may mask heterogeneous glucose profiles | Diagnosis and monitoring of diabetes; risk stratification based on average glycemia | Low–moderate cost; widely available |
| Oral glucose tolerance test (OGTT) | Detect impaired glucose tolerance and characterize post-load glycemic response | Venous blood (fasting and post-glucose load) | Short-term dynamic response (0–120 minutes, sometimes extended) | Sensitive to early dysglycemia; captures postprandial hyperglycemia not seen with FPG or HbA1c; enables derivation of insulin secretion and sensitivity indices | Time-consuming; poor reproducibility; influenced by acute factors (diet, activity, illness); limited reflection of day-to-day glycemic patterns; impractical for routine follow-up | Diagnosis of impaired glucose tolerance and diabetes in selected cases; metabolic phenotyping in research | Glucose tolerance and diabetes in selected cases; metabolic phenotyping in researchModerate cost; available but limited by logistics |
| Continuous glucose monitoring (CGM) | Characterize real-time glucose dynamics and glycemic variability | Interstitial glucose via subcutaneous sensor | Minutes to days or weeks (diurnal and short-term patterns) | Captures postprandial excursions, nocturnal hypoglycemia, and glycemic variability; identifies “hidden” dysglycemia despite normal HbA1c; high temporal resolution | Higher cost; limited access in some settings; requires technical expertise and patient adherence; clinical thresholds outside diabetes are not fully established | Selected patients with suspected glycemic instability, discordant conventional markers, or for metabolic phenotyping, research applications | High cost; accessibility varies by health system |
FMMD: Investigation, Writing—original draft. EAJC: Investigation, Writing—original draft. MMRM: Investigation, Visualization, Writing—original draft, Writing—review & editing. SGC: Investigation, Visualization, Writing—review & editing. NMS: Conceptualization, Supervision, Writing—original draft, Writing—review & editing. All authors read and approved the submitted version.
Nahum Méndez-Sánchez, who is the Associate Editor and Guest Editor of Exploration of Digestive Diseases, was not involved in the decision-making or the review process of this manuscript. The other authors declare no conflicts of interest.
Not applicable.
Not applicable.
Not applicable.
Not applicable.
Not applicable.
© The Author(s) 2026.
Open Exploration maintains a neutral stance on jurisdictional claims in published institutional affiliations and maps. All opinions expressed in this article are the personal views of the author(s) and do not represent the stance of the editorial team or the publisher.