前几篇文章，我们讲过，人工胰腺（Artificial Pancreas Systems，APS），又称为闭环系统（Closed-Loop System，CLS） 或 自动胰岛素输送系统（Automated Insulin Delivery Systems，AID），是目前治疗1型糖尿病最先进的治疗方案。
In this article, let's take a look at how it works and what it consists of.
01 The working mode of the body's own pancreas sugar regulation
The artificial pancreas simulates the physiological insulin secretion pattern of normal people for insulin infusion, so how does the pancreas regulate sugar?
[Popular science written on the front]
As shown in the diagram below, the pancreas helps maintain blood sugar stability by secreting two key hormones, insulin and glucagon.
As shown in the yellow link: after you finish eating, the carbohydrates in the food will be broken down into glucose and enter the bloodstream, and the blood sugar will rise.
At this time, the β cells of the pancreas release insulin, which acts as a signal to the body's cells that "it's time to absorb sugar from the blood."
→ As a result, tissues such as muscles, brain, and fat begin to absorb glucose, and the liver converts excess glucose into glycogen for storage—and blood sugar levels come down.
As shown in the blue link: You haven't eaten for a long time, or you have been exercising for a long time, your blood sugar will drop.
At this time, the α cells of the pancreas release glucagon, which acts as if to tell the liver, "We need more sugar for energy." ”
→ As a result, the liver breaks down previously stored glycogen into glucose, which is released into the bloodstream – blood sugar slowly rises.
02 The difference between the glucose-regulating mechanism of human pancreas and artificial pancreas
The normal human pancreas is a delicate self-regulating system that keeps blood sugar stable. Patients with type 1 diabetes need to rely on exogenous insulin therapy for life due to the destruction of their own β cells.
Automatic cybernetics includes (1) input information, (2) central processing unit, and (3) output information, which form a closed-loop regulation.
It is inferred that the artificial pancreas is: (1) blood glucose sensing and issuing commands (blood glucose sensing device), (2) regulating the secretion of insulin and other related hormones (central processing unit), (3) secreting insulin to cause blood sugar changes (pump output of insulin or other hormones to regulate blood glucose), and then feeding back to the blood glucose sensing system to simulate the human feedback system.
It can be understood in layman's terms:
● Input information: Continuous glucose meter (CGM) monitors blood glucose levels in real time
● CPU: The control algorithm calculates how much insulin to take based on blood glucose
● Output information: Insulin pump insulin
Objectively speaking, due to technical limitations, all artificial pancreas systems are not perfect at present, and the hypoglycemic mechanism of human physiological models is still different.
In terms of blood glucose perception:
The human pancreas can directly sense blood glucose in the portal venous system, and will also integrate parameters such as diet, exercise, hormones, and emotions to perceive it in real time and instantly.
The artificial pancreas relies on CGM to measure glucose levels in interstitial fluid, with delays.
Central processing of blood glucose information:
The human pancreas is a whole, and it will automatically and sensitively regulate the amount and frequency of insulin secretion by integrating various complex factors.
Artificial pancreas is currently "semi-automated", and large doses before meals still need to rely on experience to determine the dosage and manual infusion.
Blood glucose information processing output:
The human pancreas regulates blood sugar through multiple pathways such as insulin, glucagon, and intestinal hormones.
The artificial pancreas is not yet available, and it needs to rely on artificial input of carbohydrates, insulin infusion and other information for automatic adjustment.
▲Source: Professor Zhao Xiaolong's speech
The current regulatory mode of AID differs from the physiological mode of action
▲The development of artificial pancreas is currently in the 4th stage
[3] The composition and principle of artificial pancreas
Artificial pancreas can be divided into commercial artificial pancreas and DIY (open source) artificial pancreas according to whether they are approved for marketing or not, but their three key components are
●Insulin pumps
●Continuous glucose monitoring system (CGM)
● Control algorithms
Some systems may require additional widgets, such as RileyLink.
▲AAPS composition
The above figure shows the composition of AAPS (Android APS) in the open-source artificial pancreas, and its working principle is shown in the following figure:
To put it simply, the core of this system is the control algorithm (a software in Android phones, the software name is AAPS).
The patient manually enters the amount of carbohydrates and other information in the AAPS software on the mobile phone, and sets the target blood glucose level, and the AAPS software will automatically calculate the insulin dose to be infused through a series of intelligent algorithms and control the pump for infusion.
At the same time, the closed-loop system continuously monitors the patient's blood glucose level and trend, predicts blood glucose changes by analyzing the deviation between the actual blood glucose and the target blood glucose, and intelligently increases, decreases, or stops insulin infusions to achieve precise control of blood glucose.
【4】怎么用上Android APS
If you want to use the AAPS artificial pancreas, you need to prepare the following components:
(1) CGM (used to monitor blood glucose): for example, Abbott, Dekang, Silicone, Weitai, Sannuo
(2) Android phones (used to install AAPS software): for example, Google, Huawei, Xiaomi, OPPO, Vivo
(3) Insulin pump (used for insulin infusion): e.g., Danner R/RS, Micro Tither pump (scientific research pump)
*Weitai Dongtai, Silicon-based Dynamic, and Sannuo Aikan belong to domestic CGM, which are connected to AAPS by the sugar circle technical team.
The newly launched Weitai 2nd generation (AiDEX X) and European M8 will also be supported soon~
AAPS is an open source closed loop, if you know how to compile code, you can find open source code on the Internet and build it yourself.
This can be technically difficult for most people.
If you want to be the first to experience the controlled efficacy of AndroidAPS →
You can participate in the project of "Application Research of DIY Hybrid Closed-loop Artificial Pancreas System in Chinese Type 1 Diabetes Patients" in Tangtangquan (Shenzhen Aibaowei Biotechnology Co., Ltd.) and the Third Affiliated Hospital of Sun Yat-sen University.
*After we can, but we may desensitize insulin data and CGM data during use for clinical research.
If you are worried about the complexity of AAPS operation and do not know how to use →
After purchasing an insulin pump in the sugar circle, the medical team will be provided with 4 weeks of fine sugar adjustment service for free, teaching you to control sugar independently.
There is also a community of sugar friends who exchange ideas with each other.