I'm struggling with this explanation Owen to be honest. It seems to contradict a lot of what I've read. Presumably you're primarily talking about the medicated diabetic population here not non diabetics. I'm not on medication and don't suffer hypos but a lot of the medical advice would have me around 4 5 on waking and not in the 6 & 7's.
The situation would presumably be different in terms of cardiac risk for diabetics not subject to the control of medication because their 'autonomic control of their metabolic systems' is still functioning to some extent?
Primarily type 1 and insulin using type 2. Every time you are below 5 mmol, there is an increased demand on the heart to ensure the brain gets its hit of glucose. By using insulin we are trying stop too much glucose from clogging up the system but in doing so we are adding this pressure to the heart. Hypoglycaemia especially during the night adds even more risk to cardiac arrest. In addition to this when hypo's go below 3 mmol, there is a very real threat of irreversible brain damage or convulsions.
Diet controlled BM does not generally cause any of these problems.
Pumps are less of an issue as they cause less hypoglycaemic events.
All too often and myself included, we try to achieve normal BM through Insulin or blood sugar reducing drugs. We are diabetic, we are not normal. Unfortunately we are also supressing the delivery of glucose which is essential for homeostasis. We cannot sustain this tight a control without causing hypo's. Second to this, the average population are not at as high a risk of MI as are diabetics. So they can happily run their blood sugar lower.
There was a study involving type 1' having CGM and continuous ECG monitoring. The ones with tight control all showed arrhythmias or similar events during the night time when they were less aware of their BM and less able to correct it.
At the end of the day, people can shoot me down over this. I have personal experience of attending diabetics during the night in cardiac arrest. They do not fair well. Less than 10% of pre-hospital cardiac arrests survive and those that do often have severe cerebral impairment.
With all this said and done, I would rather sit above 5 and below 8. Less risk of cardiac arrest and also less risk of complications.
Hypoglycaemia is a severe medical emergency! Not a challenge to achieve.