Looking at the ranges quoted on this site for non-diabetic ranges, they look a bit tighter than Daibell's post:
Target Levels
by TypeBefore meals
(pre prandial)2 hours after meals
(post prandial)
Non-diabetic4.0 to 5.9 mmol/Lunder 7.8 mmol/L
Type 2 diabetes4 to 7 mmol/Lunder 8.5 mmol/L
As a non- medicated T2, I am almost always low 4s, fasting, with fairly regular mid-3s with no ill effects. As I understand it, for non-diabetics, under 3 is the marker for clinical hypoglycaemia, although many people feel rough, under 4. Everyone's body will find their own "comfort zone" based on their physiology, diet, medication and probably social factors.
I wouldn't know how to advise you kingstonmatt, but sticking with a diabetes friendly diet, along with watching your weight and blood pressure would seem to make sense. Or perhaps ask your quack for an MOT, based on family history? That would likely provide a fuller blood profile, including cholesterol levels. Of course, if it reveals higher than desired blood glucose readings, you would have to cope with the psychological impact of a diagnosis.
Keep fighting the good fight.