| SPINA-GR | |
| Purpose: | Medical diagnosis, research |
| Test Of: | Insulin sensitivity |
| Reference Range: | 1.41–9.00 mol/s |
| Calculator: | https://doi.org/10.5281/zenodo.7479856 |
SPINA-GR is a calculated biomarker for insulin sensitivity.[1] It represents insulin receptor gain.
The index is derived from a mathematical model of insulin-glucose homeostasis.[2] For diagnostic purposes, it is calculated from fasting insulin and glucose concentrations with:
{\widehat{G}}R=
| {G | |
| 1 |
P(infty)({D}R+\left[I\right](infty))}{{G}E\left[I\right](infty)[G](infty)}-
| {D | |
| R |
[''I''](∞): Fasting Insulin plasma concentration (μU/mL)
[''G''](∞): Fasting blood glucose concentration (mg/dL)
G1: Parameter for pharmacokinetics (154.93 s/L)
DR: EC50 of insulin at its receptor (1,6 nmol/L)
GE: Effector gain (50 s/mol)
P(∞): Constitutive endogenous glucose production (150 μmol/s)
Compared to healthy volunteers, SPINA-GR is significantly reduced in persons with prediabetes and diabetes mellitus, and it correlates with the M value in glucose clamp studies, triceps skinfold, subscapular skinfold and (better than HOMA-IR and QUICKI) with the two-hour value in oral glucose tolerance testing (OGTT), glucose rise in OGTT, waist-to-hip ratio, body fat content (measured via DXA) and the HbA1c fraction.[1]
Both in the FAST study, an observational case-control sequencing study including 300 persons from Germany, and in a large sample from the NHANES study, SPINA-GR differed more clearly between subjects with and without diabetes than the corresponding HOMA-IR, HOMA-IS and QUICKI indices.[3]
Together with the secretory capacity of pancreatic beta cells (SPINA-GBeta), SPINA-GR provides the foundation for the definition of a fasting based disposition index of insulin-glucose homeostasis (SPINA-DI).[3]
In combination with SPINA-GBeta and whole-exome sequencing, calculating SPINA-GR helped to identify a new form of monogenetic diabetes (MODY) that is characterised by primary insulin resistance and results from a missense variant of the type 2 ryanodine receptor (RyR2) gene (p.N2291D).[4]
In lean subjects it is significantly higher than in a population with obese persons.[1] In several populations, SPINA-GR correlated with the area under the glucose curve and 2-hour concentrations of glucose, insulin and proinsulin in oral glucose tolerance testing, concentrations of free fatty acids, ghrelin and adiponectin, and the HbA1c fraction.[3]