SPINA-GR

SPINA-GR is a calculated biomarker for insulin sensitivity. It represents insulin receptor gain. SPINA is an acronym for "structure parameter inference approach".

How to determine G_R

The index is derived from a mathematical model of insulin-gluose homeostasis. For diagnostic purposes, it is calculated from fasting insulin and glucose concentrations with:

${\widehat {G}}_{R}={\frac {{G}_{1}P(\infty )({D}_{R}+\left[I\right](\infty ))}{{G}_{E}\left[I\right](\infty )[G](\infty )}}-{\frac {{D}_{R}}{{G}_{E}[I](\infty )}}-{\frac {1}{{G}_{E}}}$.

[I](∞): Fasting Insulin plasma concentration (μU/mL)
[G](∞): Fasting blood glucose concentration (mg/dL)
G₁: Parameter for pharmacokinetics (154.93 s/L)
D_R: EC₅₀ of insulin at its receptor (1,6 nmol/L)
G_E: Effector gain (50 s/moL)
P(∞): Constitutive endogenous glucose production (150 µmol/s)

Clinical significance

Validity

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.

Pathophysiological implications

In lean subjects it is significantly higher than in a population with obese persons.

See also

• SPINA-GBeta
• SPINA-GD
• SPINA-GT
• Homeostatic model assessment
• QUICKI