US 2025/0375574 A1 · METHOD FOR IMPROVING BLOOD GLUCOSE CONTROL OF A HYBRID CONTROLLER

Abstract

A method for improving blood glucose control of a hybrid controller meal and exercise announcement by substituting patient-initiated meal boluses of said hybrid controller by an automatic insulin correction signal without retuning of said hybrid controller, and by incorporating rescue carbohydrates suggestion for hypoglycemia mitigation, comprising the steps of measuring a plasma glucose (G(t)) signal by means of a continuous glucose monitor (CGM), calculating a glucose level (Ĝ(t)) by using a glucose-insulin model; computing a disturbance term d(t), generating a virtual signal uIMC(t), for mitigating the effect of d(t) on the output, by means of an IMC filter Q(s) and converting the virtual signal uIMC(t) into three feed forward actions: insulin infusion, rescue carbohydrate suggestion, and insulin-on-board reduction.

Method for improving blood glucose control of a hybrid controller, eliminating meal and exercise announcement by substituting patient-initiated meal boluses of the hybrid controller by an automatic insulin correction signal without retuning of said hybrid controller, and incorporating rescue carbohydrates suggestion, the method comprising the steps of:

measuring a plasma glucose (G(t)) signal by means of a continuous glucose monitor (CGM);
calculating a glucose level (Ĝ(t)) by using a glucose-insulin model (M) describing the effect of insulin and rescue carbohydrates on glucose;
computing a disturbance term d(t) as:
d
⁡
(
t
)
=
G
^
(
t
)
-
G
⁡
(
t
)
generating a virtual signal uIMC(t), for mitigating the effect of d(t) on the output, by means of an IMC filter Q(s), defined as:
Q
⁡
(
s
)
=
u
IMC
(
s
)
d
⁡
(
s
)
=
F
⁡
(
s
)
·
H
-
1
(
s
)
wherein s is the Laplace variable, H(s) is given by the linearization of the model M with respect to insulin input, and filter F(s) is defined so that the degree of the numerator of Q(s) is lower than the degree of the denominator of Q(s);
converting the virtual signal uIMC(t) into three feedforward actions:
insulin infusion, rescue carbohydrate suggestion, and insulin-on-board reduction by:
setting insulin uins(t) to 0 if uIMC(t) is lower than a positive threshold thins;
matching uins(t) to uIMC(t), to add insulin to the main controller, limited by an upper saturation threshold thsat, if uIMC(t) is higher than thins, or subtract insulin from the main controller, when uIMC(t) is below the negative threshold thresc:
converting the negative-valued insulin uIMC(t) into rescue carbohydrates suggestions (uresc), then zeroing uins(t) to avoid both types of control actions coupling each other if uIMC(t) is lower than thresc, comprising conversion of negative insulin into rescue carbohydrate suggestions the steps of:
generating a virtual unquantized carbohydrate signal, uint(t), integrating uIMC(t) in a sliding window of length tw, as follows:
u
int
(
t
)
=
-
k
resc
⁢
∫
t
-
t
w
t
u
IMC
*
(
τ
)
⁢
W
⁡
(
τ
)
⁢
d
⁢
τ
-
∫
t
-
t
w
-
T
s
t
-
T
s
u
resc
(
τ
)
⁢
W
⁡
(
τ
)
⁢
d
⁢
τ
using a variable
u
IMC
*
instead of uIMC to avoid suggesting rescue carbohydrates when insulin inhibition may suffice, calculated as:
u
IMC
*
(
t
)
=
{
u
IMC
(
t
)
if
u
IMC
(
t
)
≤
th
resc
0
otherwise
and where Ts is the sampling time, kresc is a gain for converting “negative insulin” into rescue carbohydrate suggestions and W(t*) is a forgetting factor that attenuates the earlier values of
u
IMC
*
(
t
)
by using a monotone non-decreasing function W(t*), which has values for t*∈[t−tw, t], where t refers to the current time and t−tw the beginning of the sliding window, and so that W(t)=1
calculating uresc(t) by:
u
resc
(
t
)
=
{
⌊
u
i
⁢
n
⁢
t
(
t
)
⌉
·
if
⁢
u
i
⁢
n
⁢
t
(
t
)
≥
0.5
and
G
*
⁢
(
t
)
≤
C
2
⁢
and
⁢
Δ
⁢
t
resc
>
C
1
if
⁢
G
*
(
t
)
≤
C
3
⁢
and
CGM
⁢
(
t
)
≤
C
2
⁢
and
⁢
Δ
⁢
t
resc
>
C
1
0
otherwise
wherein └⋅┐ denotes the nearest integer operator, is the quantization level, Δtresc is the elapsed time between two consecutive rescue carbohydrate suggestions, C1 is a parameter introduced as a delay for avoiding consecutive rescue carbohydrate suggestions, C2 and C3 are parameters related to mild and moderate hypoglycemia thresholds, and G*(t) is a glucose prediction.

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Method for improving blood glucose control of a hybrid controller

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Method for improving blood glucose control of a hybrid controller

Life of this patent

Abstract

Claims24