Most of those people - very likely some of you - don't know it.
It's the same story globally. In the US, recent research estimated half of all adults have either type 2 diabetes or prediabetes.
The burden on the health system will be huge.
And we are heading in a similar direction. Even if we're healthy, we'll all be paying for this in some way.
So what is to be done?
For Diabetes Action Month, Diabetes New Zealand is aiming to put the power in the hands of the people.
Its research has revealed less than half of those living with diabetes feel they are in control of their condition, and a third said it had a negative effect on their mental wellbeing.
It's common for people to feel powerless when faced with a diagnosis of type 2 diabetes, or to believe that the disease is an inevitable thing.
Felila Taupau, 38, who was diagnosed three months ago, is typical.
Her mother died from diabetes. "I used to think that diabetes ran in the family so I couldn't change it. Now I know different."
She has been trialling the Take Control Toolkit; a comprehensive online support and self-management toolkit, developed by Diabetes New Zealand for people with diabetes.
Felila has lost more than 10kg using the toolkit for just six weeks, and even better, she's passing on her new healthy habits to the next generation.
"The fridge used to be full of fizzy every week but we drink water now. We love our veges, I always try to feed my children vegetables now.
"We do lots more activity as a family and the kids are always asking how my steps are going and asking about diabetes and so we are all learning about it."
The Take Control Toolkit has over 60 online print and video resources for Diabetes New Zealand members.
It has practical advice including simple ways to test your fitness; how to read food labels; dealing with the stress and depression; and a 12-week walking plan.
There are also tools for family and friends supporting someone with diabetes - an important part of the picture.
Type 2 diabetes can't be cured.
But it can be managed well so people can live active and healthy lives.
A diagnosis does not have to mean the start of a slow decline; but it does take a bit of action and some lifelong habit changes.
World Diabetes Day is 14 November idf.org/wdd-index/
Lean more about Diabetes at diabetes.org.nz/home
