The numbers of people with diabetes is expected to rise
Only 2% of diabetics are attending classes set up to help manage their condition, according to research for the BBC's Eye on Wales programme.
A national framework was set up in 2003 to ensure those diabetics were offered education to manage their condition.
The assembly government said structured education was "patchy" and added it needed to give it greater priority.
Diabetes UK Cymru said to do nothing was a false economy and could lead to a "catastrophe" within the population.
Statistics obtained by the organisation show around 42 people with diabetes in Wales will have a heart attack every week and five people will have a limb amputation.
The cost to the nation is 10% of the overall NHS budget - £500m or £55,000 an hour.
Around 5% of the population have diabetes but that figure is expected to double in the next 10 years.
Experts agree that better screening services, education and awareness is the best way to tackle the issue.
In Carmarthenshire, a six-week course has been set up to offer patients advice on how to manage their condition and how to prevent other diabetes-related diseases developing.
Richard Thomas, who was diagnosed with type two diabetes, attended such a class.
"The course has made such a difference... they motivate you so much. I'm going to live with diabetes - it hasn't beaten me and it won't," he said.
But research has shown only 2% of patients have attended such courses and questions over the consistency of services have been raised.
Liberal Democrat health spokesman Peter Black said: "Parts of Wales, you can go and you can be diagnosed early, you can get the treatment you need.
"In other parts of Wales that doesn't happen, and clearly that is a discrepancy which the government needs to address as part of rolling out this strategy."
Dai Williams of Diabetes UK Cymru added: "To not do anything is a false economy.
"It's going to lead to a catastrophe within the population.
"A small amount of money spent on structured education, we would save ourselves a fortune in Wales and spend the money where it's really needed."
In response, a Welsh Assembly Government spokesperson said it recognised the value of providing structured education to help patients manage their condition but said it was not appropriate in all cases.
He added that despite not all attending courses, education was provided to those with diabetes.
"We recognise that structured education is still patchy across Wales and that we need to improve this by giving it a greater priority," he said.
He added that monitoring the NHS progress with implementing the Diabetes National Framework was being stepped up with local health boards being asked to put delivery plans in place.
He added: "In performance-managing the NHS on progress with their plans, officials will challenge the need to give a higher priority to structured education."
Eye On Wales is on BBC Radio Wales at 1830 BST on Monday 22 June.