Health professionals are warning of an "incipient health crisis" following funding cuts to healthy eating and obesity prevention programmes.
The warning came in an open letter to the New Zealand Medical Journal signed by 12 medical specialists, public health researchers and nutritionists.
It said the Government was not doing enough to combat increasing diabetes rates and the axing of programmes such as the Healthy Eating Health Action strategy could lead to a health crisis.
An increase in the number of people suffering from diabetes could largely be attributed to rising obesity rates, the letter said.
Between 1989 and 1997 the average weight gain in adults was 3.2kg.
"Obesity accounts for more than 80 per cent of preventable diabetes in New Zealand and is not being vigorously addressed, in fact many preventive programmes have been cut," University of Otago public health researcher Associate Professor Louise Signal said.
"We have alarmingly high rates of diabetes, they're getting worse, and we compare very poorly with other OECD (Organisation for Economic Development and Co-operation) countries, according to the June edition of the British journal the Lancet.
"Health professionals have been warning about this incipient health crisis for years."
Prof Signal said 63 per cent of adults were overweight or obese and two to seven per cent of the health budget was being spent on weight-related problems, such as diabetes and diabetes-related kidney failure.
Such problems were disproportionately high in Maori, Pacific Island and low income New Zealanders, she said.
The letter identified nine "urgent preventive actions", including the introduction of a "traffic light" nutritional labelling programme, the promotion of physical activity, and a ban on marketing junk food to children.