Hi
@EllieM and thank you
@Knikki for the tag! As a T1D, not as professional advice or opinion:
Important take-home message is (according to my DNE who was very insistent I understood)
With injecting a long acting insulin like Lantus the depot or reservoir of insulin is under your skin.
In an insulin pump, the depot or reservoir of insulin is in the pump.
The drug company will quote from their studies how soon say, Lantus or other long acting insulin, appears in the blood stream (of a human), whether and when it reaches a peak of effect (or not) and for how long the insulin stays active in the body.
Also some pharmaceutical reports by the company will show that the higher the dose of say, Lantus, the longer it has an effect in the body.
You can google this under
'pictures and insulin profiles' and
drug company monographs and compare Lantus's profile to that of one of the short-acting insulins used in an insulin pump. These results are going to be averages of sorts, so for some people Lantus might last 30 hours, in others longer or shorter per same dose
So you forget to take your 10 pm evening dose of Lantus and let us assume that your last dose was about the same time, 24 hours ago. Drug company profiles for Lantus suggest (but not prove) that after the time of the missed dose there will be a low trickle of 'left-over' insulin activity over ? 4 ? 6 ? longer hours
Whether that activity is enough to stop ketones forming depends on many things such as when and what one last ate, the dose of Lantus 24 hours ago, any short-acting insulin taken the evening of the missed dose of Lantus etc.
So by 6 am the next morning after the missed dose of Lantus some insulin
may still be present in a truly insulin-dependent person. But not guaranteed.
On the other hand
if my insulin pump stops delivering insulin altogether at 10 pm, it has the remnants of short acting insulin bolus for the evening meal, say at 6 pm. There may be only 2 and a bit hours worth of dwindling insulin effect from the bolus dose by 10 pm, as the insulin is short-acting in type. Add to that a small amount of basal insulin say approx. 5.7 units spread over hours 6 pm to 10 pm - so the insulin effect is likely to last to maybe 4 am. but that last gasp of insulin is, in my case, from 0.525 units of short-acting insulin delivered at 9.30 pm. Again the variables are as for missed Lantus dose but the last dose of short-acting insulin is quite small.
So which person is in more trouble? I would say I am as there is nothing there under the skin to be absorbed some hours before 6 am and if I have any DP effect that could exaggerate things.
The other variables which might apply are things that could change insulin resistance such as current illness, stress etc, and exercise in the past 24 hours approx.
I hope that helps explain things.
With insulin pumps my experience is that the most troublesome pump delivery troubles are that the cannula which is situated under the skin can become partially obstructed by becoming bent or kinked but not enough to trigger an alarm, or other times the insulin may leak from the cannula tip back up under the adhesive patch holding the needle port in place. Yes, accidental pulling out of cannulas or unsticking of needle ports can occur too. Pumps can fail but that is much less common.
So BSLs rise pretty quickly with the above most troublesome problems and provide the dilemma of whether to change the needle port/cannula or not. I have certainly started to develop ketones within 4 hours of the assumed bent cannula problem having tried larger than usual bolus pushes to see whether the issue might be something else.
Of course our wonderfully generous health systems could oblige by giving us pumpers each a special ultrasound device (with foolproof instructions in my case) to detect kinks and bends in the cannula and perhaps leaking cannulas, and special alert systems for detachment of cannulas!!! In a perfect world anything is possible.
