The Deakin University study, published in the Diabetes, Obesity and Metabolism journal, found taking two 500mg doses daily can lower elevated blood sugar levels and reduce post-meal blood sugar spikes in type 2 diabetics.

"We found that participants had a significant 36 per cent drop in the blood sugar spike after meals. This also meant that they spent almost three hours less per day living in a state of hyperglycaemia," lead researcher associate professor Glenn Wadley said on Monday.

"This is extremely positive news as hyperglycaemia is a risk factor for cardiovascular disease in people living with type 2 diabetes."

More than 1.2 million Australians have been diagnosed with the disease.

The dose of vitamin C used in the randomised study was about 10 times the normal dietary intake and readily available at most health food stores.

"Vitamin C's antioxidant properties can help counteract the high levels of free radicals found in people with diabetes, and it's encouraging to see this benefits a number of the disease's common comorbidities, such as high blood pressure," Professor Wadley said.

"For people living with type 2 diabetes, vitamin C could be a potentially cheap, convenient and effective additional therapy, used in addition to their usual anti-diabetic treatments."

Study participants with hypertension also had their blood pressure levels drop while taking the vitamin C tablets, he added.

Australian Associated Press