Dr Coppell, who is a senior research fellow at the university's Edgar National Centre for Diabetes and Obesity Research, gave a paper on the prevalence of diabetes and pre-diabetes at an international health conference at the university this week.
The massive toll on patients, their families and the economy resulting from the growing surge in type 2 diabetes was "incredibly serious", she said in an interview.
Studies conducted in Finland and elsewhere have showed that people at high risk of developing type 2 diabetes can greatly improve their health outcomes, including avoiding diabetes, by increasing exercise and adopting a more balanced diet, with less saturated fat and sugar.
Dr Coppell said greater emphasis was needed from government in promoting such positive lifestyle changes, to reduce obesity and lessen risks of developing type 2 diabetes.
The provision of insulin, some diabetes-related medication and blood-testing strips already cost the country more than $50 million a year.
Other drugs, including cholesterol-lowering medication, and other requirements, including dialysis treatment, added considerably to current medical costs.
But the "actual burden of disease" had been underestimated, because previous national diabetes prevalence estimates had not included undiagnosed cases.
Analysis of data from the 2008-09 New Zealand Adult Nutrition Survey and associated research involving several of her colleagues, including centre director Prof Jim Mann, showed 6% of New Zealand men and 4% of women reported having medically confirmed diabetes.
However, further research showed another 2.1% of men and 1.5% of women also had previously undiagnosed diabetes.
Such overall diabetes prevalence figures were higher among Maori men and women (8.8% and 9.8% respectively), and among Pacific people.
Further adding to concerns was another sizeable group of people with a pre-diabetic condition which was likely to lead to diabetes in the future.
The Otago International Health Research Network's fifth annual conference has been organised by the Otago Centre for International Health.