That’s already the concept of insulin pumps. The problem currently is that subcutaneous insulin takes too long to work to be very precise, and also, pumps don’t have a concept of carb intake. They try to predict whether automatic doses are need based on trends. Also, typical blood glucose for a non-diabetic person is 85 mg/dL. This is fairly close to the line of hypoglycemia, which is under 70, so automated pumps aim to keep glucose somewhat higher. For the Tandem T:Slim, it attempts to maintain 110, for instance. I am not familiar with most of the drugs listed there but I suspect their action would be far too slow to work very well in that regard.
I have Type 1 Diabetes (T1D) and use a semi-closed loop system, which includes the Libre 2 sensor with XDrip and the Omnipod Dash, managed by AAPS.
AAPS (unlike the Tandem T
, which I’m less familiar with) uses a more sophisticated algorithm to calculate the required insulin, considering several factors:
- Blood sugar levels received via XDrip from the Libre 2 sensor.
- A profile that includes:
- - The basal rate per hour for each time slot
- - The insulin-to-carb ratio
- - The target blood sugar range
- Automatically calculated insulin sensitivity.
- Insulin on board (remaining active insulin), calculated using a curve to estimate how much insulin is still active after injection.
- Carbs on board, with AAPS tracking active carbs over time.
I've heard that AAPS is more sophisticated. I'm definitely not too happy with the Tandem system. Some people say they get better levels with Control IQ, but I don't. The T:Slim does have the ability to set basal rates for different times of day, and takes as input your insulin to carb ratio, correction ratio, weight, and tracks IoB. I don't think the insulin on board algo is very good... it starts decreasing before I see any effect on my glucose, and dissipates quicker than I expect. They base it on insulin lasting 5 hours, I think, but it seems to calculate less time. It's not a 'learning' algorithm either afaik.
The lack of carbs is perhaps the worst for me. Even if I track then on the Dexcom app, it doesn't use them. The automatic boluses are often wrong. When I had it anywhere near my real ratio, it would 'predict' I was going over 160 and automatically dose me. So, say I was at 85, and had 15 grams of potato chips. My glucose would rise quickly and as it went over 125, 140, the system would predict it was going up past 160 - or who knows, since it doesn't know how many carbs I ate. So then it would dose me with say, 1.1 units, which was enough to take my glucose -back to 85-. That sent me in loops a couple of times... 85, eat, up to 145, automatic bolus, back to 85, eat, up to 145 - very annoying when it happened at night. I had to set my carb ratio so high that the automatic boluses are now insignificant amounts like .16 units. It also doesn't notify you on your phone about automatic boluses, which has caused me major problems when I'd also manually correct. The automatic basal reduction (Basal IQ) is useful though.
Anyhow, I'd love to try AAPS but I don't have an Android phone. I also used to follow someone on Twitter who was developing his own software that he said removed the need to pre-bolus at all. Not sure about the details though.
I switched from iOS to Android for AAPS ( i didn't want to carry two phones )
With AAPS - it is usually able to deal with my blood sugars at night automatically.
During holidays ( 0 stress day), AAPS can almost completely determine boluses just based on my profile and carb intake. ( i.e. I don't force a bolus )
However, during normal workdays, I usually need to bolus right before carb intake. AAPS also allows you specify bolus a percentage and then let it figure out the rest automatically.
We could, I guess, with some biochemical wizardy. Insulin does more than just reduce blood glucose, though. It allows the glucose to enter muscle and brain cells to be used for energy. People with Type 1 need just as many carbs and as much energy as other people, of course, it's just that their body can't use it properly. Insulin does have the drawback of being a fat storage hormone though. Such a device sure would be great for people who indulge in too many carbs!
