. 2016 Apr 12;5:647. [Version 1] doi: 10.12688/f1000research.8299.1

Table 1B. Glucose equations (number prefixes refer to positions in Figure 1).

1 I n t e s t i n a l G l u c o s e a b s o r p t i o n r a t e = (S G L T 1 G l u c o s e p u m p * \frac{i n t e s t g l c}{(i n t e s t g l c + S G L T 1 K m))} + P g l * (i n t e s t i n e l u m e n g l c - S m c a p g l c))

2 \int_{t = 0}^{t = t x} \frac{d}{d t} (S y s V G l u c o s e) = d / d t (S y s V e i n G l c) = + r e n a l v g l c f l o w + H V g l c f l o w + s o m V g l c f l o w - V e n a g l c f l o w + H e p s h u n t g l c f l o w

\int_{t = 0}^{t = t x} \frac{d}{d t} (h e p a t i c g l c) = d / d t (h e p g l c) = H A g l c f l o w + P V g l c f l o w + s p l e n i c V g l c f l o w - H V g l c f l o w - h e p g l c m e t a b o l i c r a t e

4 B

H e p a t i c g l u c o s e m e t a b o l i c r a t e = (V_{m a x} G L U T 2 * \frac{G l c_{H e p}}{K_{M G l u t 2} + G l c H e_{p}}) * \frac{I n s_{(h e p)}}{K_{i n s} + I n s_{(h e p)}} * H e p i n s e n s * (1 + G L P_{(h e p)} V m a x * \frac{G L P}{K_{m G L P} + G L P_{(h e p)}})

5 \int_{t = 0}^{t = t x} \frac{d}{d t} (S y s t e m i c g l c) = d / d t (S y s t e m i c g l c) = a f f e r e n t s y s t e m g l u c o s e f l o w - s y s t e m i c V g l c f l o w - s y s i n s u l i n - d e p g l u c o s e m e t a b o l i c r a t e - p e r i p h e r a l i n s u l i n - i n d e p e n d e n t m e t a b o l i c r a t e .

6 R e n a l u r i n e g l u c o s e f l = (R e n a l g l u c o s e f l o w * 0.1 - (T m S G L T 2 * \frac{G l c_{R e n a l A}}{G l c_{R e n a l A} + K m S G L T 2})

7 \int_{t = 0}^{t = t x} \frac{d}{d t} (S M c a p g l c) = d / d t (a f f e r e n t S M A g l c f l o w + i n t e s t i n a l g l c a b s o r p t i o n r a t e - P o r t a l v e i n g l u c o s e f l o w - h e p a t i c s h u n t g l c f l o w)

Intestinal absorption,
Intestinal absorption rate Glc pump is the glucose pump rate controlled by apical membrane SGLT1 V _max; Glc _{(intest.Lum.)} and Glc (SM cap)
are the glucose concentrations, mM in the intestinal lumen and superior mesenteric capillary network, operational K _m is the affinity of
SGLT1 activated pump is taken as 17 mM ^16,
17 (Debnam & Levin, 1975 b).

Intestinal glucose absorption rate = V _max _SGLT1 * (Glc _{(intest lumen)}/(Glc _{(intest lumen)} + K _{m (SGLT1)}) + Pgl *(Glc _{(intest lumen)}- Glc _{(SM_cap)}).

Net hepatic glucose uptake and hepatic glucose metabolism
Hepatic glucose metabolic rate:-
V _max _GLUT2 is V _max of hepatic GLUT2/glucokinase, Glc _(Hep) the sinusoidal glucose concentration; K _m _GLUT2 the K _m of hepatic GLUT2 for
glucose mM; Ins _(Hep), the hepatic insulin concentration; Hepinsens, the hepatic sensitivity coefficient to insulin concentration; GLP-1_ _Hep,
the hepatic GLP-1concentration; GLN_ _Hep, the hepatic glucagon concentration nM; Hep _GLNcoef, the hepatic glucagon sensitivity. K _m. _ins,
K _{m_GLP-1}, K _mGLN are the K _ms of insulin, GLP-1 and glucagon estimated to be within the range of known blood concentrations ^47,
48 (Levy et al., 1998;
Wallace et al., 2004).

H e p a t i c g l u c o s e m e t a b o l i c r a t e = (\int h e p g l u c o s e m e t a b o l i s m = V m a x G L U T 2 * \frac{G l c H e p}{K m G l u t 2 + G l c H e p}) *

\frac{H e p I n s}{K m i n s + I n s} * H e p i n s e n s * I n s u l i n i n d e p e n d e n t m e t a b o l i c r a t e = i n s u l i n i n s e n s i t i v e m e t a b o l i c c o e f *

\frac{G l c_{s y s} A}{(G l c_{s y s} A + K m G L U T 1)} * (1 + G L P H e p) * V m a x \frac{G L P}{K m G L P + G L P H e p}) - H e p G L N c o e f * (\frac{H e p G L N}{H e p G L N + K m G L N}))

Renal glucose excretion.

R e n a l u r i n e g l u c o s e f l o w = (R e n a l g l u c o s e f l o w * 0.1 - (T m S G L T 2 * \frac{G l c_{R e n a l A}}{G l c_{R e n a l A} + K m S G L T 2})

T h e r e n a l f i l t r a t i o n f r a c t i o n i s 10 %; S G L T 2 r e c o v e r s r e n a l t u b u l a r g l u c o s e K_{m} = 0.1 m M g l u c o s e .