Source of HOMA-IR

{{Infobox concept | name = HOMA-IR | subtitle = Derived index | Full name = Homeostatic model assessment of insulin resistance | Inputs = Fasting glucose and fasting insulin | Reference method = Hyperinsulinaemic-euglycaemic clamp }} '''HOMA-IR''' is an index of insulin resistance derived from a single fasting sample. In its original linear approximation it is the product of fasting glucose and [[Fasting insulin|fasting insulin]] divided by a constant, and it correlates moderately with clamp-derived measures of insulin sensitivity across populations.{{r|matthews1985}} Its appeal is that it requires one blood draw rather than a several-hour clamp. Its weakness is that it is a model-derived approximation from two values, inherits the poor standardisation of insulin assays, and describes hepatic rather than peripheral insulin resistance most directly.{{r|wallace2004}} The authors of the model have themselves written about its misuse, and the practical conclusion is that it tracks change within an individual on a consistent assay better than it classifies individuals against published thresholds.{{r|wallace2004}} == Calculation and the two forms == The original linear approximation is {{math|\text{HOMA-IR} = (\text{glucose}_{\text{mmol/L}} \times \text{insulin}_{\text{mU/L}}) / 22.5}} A revised non-linear computer model, HOMA2, was published later and gives different values, particularly at the extremes. The two are not interchangeable, and a figure quoted without saying which was used is ambiguous.{{r|wallace2004}} Unit conventions add a second ambiguity: glucose in mg/dL requires a different divisor, and insulin in pmol/L a further conversion. A published cut-off carries its unit convention with it.{{r|matthews1985}} Both forms assume steady-state fasting conditions, and neither has a meaning in anyone receiving exogenous insulin, since the insulin measured is then not the beta cell's output. == What it does and does not measure == | Property | Assessment | |---|---| | Correlation with clamp | Moderate at population level | | Individual classification | Poor; wide overlap between groups | | Tracking change within a person | Better, on a consistent assay | | Compartment | Reflects hepatic insulin resistance most directly | | Comparability between studies | Limited by assay and model version | The population-versus-individual distinction is the crux. A moderate population correlation is compatible with substantial misclassification of individuals, and an index that performs acceptably as a group descriptor may perform poorly as a personal one.{{r|wallace2004}} For that reason it appears widely in epidemiology and rarely in individual clinical decision-making.{{r|matthews1985}} == Behaviour under weight loss and incretin therapy == HOMA-IR falls with weight loss by any means, and the fall tracks the improvement in insulin sensitivity that accompanies reduced adiposity. This is a well-replicated finding and is not specific to any pharmacological class.{{r|drucker2018}} Under incretin therapy, both inputs move: insulin secretion is amplified while the drug is present, and sensitivity improves with weight loss. The resulting index change is therefore a composite, and attributing it to a change in sensitivity alone is unsound.{{r|wallace2004}} The index appears on many of the laboratory panels discussed in this field; see [[Baseline laboratory panel]]. Nothing on this wiki is medical advice.{{r|ada2024}} == References == {{reflist}} <ref name="matthews1985">Matthews DR, Hosker JP, Rudenski AS, et al. "Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man." ''Diabetologia'' 28(7):412–419 (1985). PMID 3899825.</ref> <ref name="wallace2004">Wallace TM, Levy JC, Matthews DR. "Use and abuse of HOMA modeling." ''Diabetes Care'' 27(6):1487–1495 (2004). PMID 15161807.</ref> <ref name="drucker2018">Drucker DJ. "Mechanisms of action and therapeutic application of glucagon-like peptide-1." ''Cell Metabolism'' 27(4):740–756 (2018). PMID 29617641.</ref> <ref name="ada2024">American Diabetes Association. "Standards of Care in Diabetes." ''Diabetes Care'' 47(Suppl 1) (2024).</ref> == See also == * [[Fasting insulin]] * [[C-peptide]] * [[Beta cell function]] * [[Insulin secretion]] * [[Baseline laboratory panel]] {{DEFAULTSORT:HOMA-IR}} [[Category:Metabolic biomarkers]] [[Category:Laboratory medicine]] [[Category:Evidence appraisal]]