This is all I could find in the actual NICE guideline
http://www.nice.org.uk/guidance/cg8...tyle-managementnon-pharmacological-management
1.3.1 When setting a target glycated haemoglobin (HbA1c):
involve the person in decisions about their individual HbA1c target level, which may be above that of 6.5% set for people with type 2 diabetes in general
encourage the person to maintain their individual target unless the resulting side effects (including hypoglycaemia) or their efforts to achieve this impair their quality of life
offer therapy (lifestyle and medication) to help achieve and maintain the HbA1c target level
inform a person with a higher HbA1c that any reduction in HbA1c towards the agreed target is advantageous to future health
avoid pursuing highly intensive management to levels of less than 6.5%.
Endquote
Presumably that last paragraph is a reference to the ACCORD study results.
Whether "highly intensive management" extents to dietary management as well as medicinal is not expanded on.