The six-month University of Otago study, Lifestyle Over and Above Drugs in Diabetes, found that providing intensive healthy diet advice would help people with diabetes control their blood sugar.
Study lead author Dr Kirsten Coppell said staving off the disease was crucial in avoiding long-term complications such as kidney failure, heart disease, gangrene and blindness.
"The patients in our study were already under intensive drug treatment to optimise their glycaemic control, which remained unsatisfactory. We found that by also following carefully tailored dietary advice they could significantly improve this control."
Dr Coppell said no matter how intensive the drug treatment, glycaemic control in high-risk diabetes patients slowly, but surely deteriorate, so the findings are relevant in improving diabetes management.
The study divided 94 diabetes patients from the Otago region into two groups. Both received medical care, but patients in one group were also given one-on-one dietary advice.
It involved tailoring advice to meet each individual's socio-economic and cultural circumstances, such as encouraging smaller meals, reducing unhealthy components in their diets and eating more fruits and vegetables.
The group receiving advice improved their glycaemic control, with some members even able to safely reduce their doses of hypoglycaemic drugs or insulin by the end of the study, Dr Coppell said.
Reduction in weight, body mass index and waistlines also occurred in the advised group.
"Since the widespread introduction of anti-diabetic drugs, the traditional focus on diet and lifestyle in managing diabetes has faded into the background. Our findings suggest that there needs to be a renewed focus on these elements if we want to improve diabetes outcomes."
"However, making and sustaining such lifestyle changes can be difficult for many people.
"Having specialist health professionals who can assess individual circumstances and provide regular advice and encouragement, as well as supportive family members, appears to be a key factor to succeeding in this."
Dr Coppell said a goal is to develop a programme involving such experts.
The study was supported by grants from the Health Research Council of New Zealand and the Southern Trust. It was published in the UK medical journal BMJ this week.