SPINA-GBeta
| SPINA-GBeta | |
|---|---|
| Reference range | 0.64–3.73 pmol/s |
| Calculator | https://doi.org/10.5281/zenodo.7479856 |
| Purpose | Medical diagnosis, research |
| Test of | Pancreatic beta cell function |
SPINA-GBeta is a calculated
How to determine GBeta
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:
.[1]
({D}_{\beta }+\left[G\right](\infty ))}{{G}_{3}[G](\infty )}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/f2f50477c6037130824999c266a2e0f28baa0099)
[I](∞): Fasting Insulin plasma concentration (μU/mL)
[G](∞): Fasting blood glucose concentration (mg/dL)
Dβ: EC50 for glucose at beta cells (7 mmol/L)
G3: Parameter for pharmacokinetics (58,8 s/L)
Clinical significance
Validity
SPINA-GBeta significantly correlates with the M value in
It has the additional advantage that it circumvents the HOMA-blind zone, which renders the calculation of HOMA-Beta impossible if the fasting glucose concentration is 3.5 mmol/L (63 mg/dL) or below.[3] Unlike HOMA-Beta, SPINA-Beta can be sensibly calculated in the whole range of measurements.[1]
Reliability
In repeated measurements, SPINA-GBeta had higher retest reliability than HOMA-Beta, a measurement for beta cell function from the homeostasis model assessment.[1][4]
Clinical utility
In the FAST study, an observational case-control sequencing study including 300 persons from Germany, SPINA-GBeta differed more clearly between subjects with and without diabetes than the corresponding HOMA-Beta index.[4]
Scientific implications and other uses
Together with the reconstructed insulin receptor gain (SPINA-GR), SPINA-GBeta provides the foundation for the definition of a fasting based disposition index of insulin-glucose homeostasis (SPINA-DI).[4]
In combination with SPINA-GR and whole-exome sequencing, calculating SPINA-GBeta 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).[5]
Pathophysiological implications
In several populations, SPINA-GBeta 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.[4]
See also
- SPINA-GR
- SPINA-GD
- SPINA-GT
- Homeostatic model assessment
- QUICKI
Notes
- ^ SPINA is an acronym for "structure parameter inference approach".