Surrogate markers of insulin resistance: A review

Table 1 Various methods to measure insulin resistance

S No	Method	Comments	Advantages	Disadvantages
1	Hyperinsulinemic euglycemic glucose clamp	Gold standard method for quantifying insulin sensitivity	Direct measure of insulin under steady-state conditions	Laborious, involves intra venous infusion of insulin, frequent blood sampling
2	Oral glucose tolerance test	Clinically used to detect glucose intolerance	Helps in estimating other surrogate indices	Useful for glucose tolerance but not for IR
3	Fasting insulin	Most practical method to measure IR	Detects insulin resistance before clinical disease appears	Lack of standardization of the insulin assay procedure
4	Glucose/insulin ratio (G/I ratio)	comparable to insulin sensitivity measured by the FSIVGTTT	Highly sensitive & specific for insulin sensitivity	Does not aptly reveal the physiology of insulin sensitivity
5	Insulinogenic index (IGI)	index of β-cell function δI (0-30 min)/δG (0-30 min)	Measure of first-phase insulin response to glucose challenge	Not broadly validated
6	Homeostasis model assessment	Assesses inherent β-cell function and insulin sensitivity HOMA-IR = (G × I)/22.5	Simple, minimally invasive, predicts fasting steady-state G and I levels	Insulin sensitivity in subjects treated with insulin needs further validation
7	Quantitative insulin sensitivity check index (QUICKI)	Mathematical transformation of FBG and insulin QUICKI = 1/[log (IμU/mL) + log(G mg/dL)]	Consistent, precise index of insulin sensitivity, minimally invasive	Normal range to be established for each laboratory due to significant inter laboratory variations in insulin assay
8	Minimal model analysis of frequently sampled intravenous glucose tolerance test	Indirect measure of insulin sensitivity/resistance	Analysis using the computer program MINMOD	Multiple blood sampling
9	Glucose insulin (GI) product	Index of whole-body insulin sensitivity
10	Fasting insulin resistance index (FIRI)	(fasting G × fasting I)/25

G: Glucose; I: Insulin; IR: Insulin resistance; FBG: Fasting blood glucose.