NICE recommended target blood glucose level ranges by Type:
Non-diabetic 4.0 to 5.9 mmol/L before meals (pre prandial) under 7.8 mmol/L 2 hours after meals (post prandial)
Type 2 diabetes 4 to 7 mmol/L before meals (pre prandial) under 8.5 mmol/L 2 hours after meals (post prandial)
Type 1 diabetes: 4 to 7 mmol/L before meals (pre prandial) under 9 mmol/L 2 hours after meals (post prandial)
Children w/ type 1 diabetes 4 to 8 mmol/L before meals (pre prandial) under 10 mmol/L 2 hours after meals (post prandial)
As you have seen from earlier posts on this thread, some people prefer and are able to keep their levels within a much tighter range than the above recommendations.
Pavlos