From the Guidelines
Insulin resistance is best assessed using the hyperinsulinemic-euglycemic clamp technique, which measures the glucose disposal rate (GDR) and is considered the gold standard, although it is primarily used in research settings due to its complexity. The assessment of insulin resistance is crucial as it predicts cardiovascular morbidity and mortality in the metabolic syndrome and type 2 diabetes mellitus (T2DM) 1. In clinical practice, several parameters are used to estimate insulin resistance, including:
- Fasting insulin levels, with elevated levels suggesting insulin resistance
- The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), which uses fasting glucose and insulin levels in a mathematical formula to estimate insulin resistance
- The oral glucose tolerance test (OGTT), which measures how quickly glucose is cleared from the blood after consuming a standardized amount of glucose
- The quantitative insulin sensitivity check index (QUICKI), another calculation based on fasting glucose and insulin values
- Additional relevant markers include glycated hemoglobin (HbA1c), triglyceride to HDL cholesterol ratio, and waist circumference, which can provide supporting evidence of insulin resistance. However, the hyperinsulinemic-euglycemic clamp technique is the most accurate method, especially in diabetes mellitus, as it directly measures insulin sensitivity by calculating the amount of glucose required to maintain normal glucose levels (euglycemia) 1. In children, the euglycemic clamp is used for research purposes only, and assessment of hyperinsulinemia by measuring fasting plasma insulin levels may provide a reasonable clinical alternative for evaluating insulin resistance 1.
From the Research
Parameters to Assess Insulin Resistance
The following parameters are used to assess insulin resistance:
- Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) 2, 3, 4, 5, 6
- Quantitative Insulin Sensitivity Check Index (QUICKI) 2, 3, 4, 6
- Triglyceride-Glucose Index (TyG index) 5
- Fasting Glucose/Insulin Ratio (FGIR) 6
- McAuley's index 3
Calculation of Parameters
These parameters are calculated using fasting glucose and insulin levels:
- HOMA-IR: (fasting insulin [μIU/mL] × fasting glucose [mmol/L])/22.5 5
- QUICKI: 1/log insulin + log glycemia in mg/dL 2
- TyG index: ln(fasting triglycerides [mg/dL] × fasting glucose [mg/dL]/2) 5
- FGIR: fasting glucose/insulin ratio 6
Validation of Parameters
Studies have validated these parameters against other measures of insulin resistance, such as:
- Hyperinsulinemic euglycemic clamp technique 3
- Oral glucose tolerance test (OGTT) 6
- Stable-labeled, frequently sampled intravenous glucose tolerance test 4
Comparison of Parameters
Comparisons between parameters have shown that: