An opportunity was missed to improve care for people with type 2 diabetes in Northern Ireland, the audit office said.
Comptroller and auditor general Kieran Donnelly said he was disappointed at limited implementation of a 2003 review pointing the way towards best practice.
He noted a failure to introduce a comprehensive strategy until late 2016.
Mr Donnelly said: "This was clearly a missed opportunity to slow the growing prevalence of the disease, and to reduce the numbers of serious complications which can arise, including blindness and lower limb amputations."
Type 2 diabetes which affects regulation of blood sugar levels by the body involves almost 6% of the adult population in Northern Ireland.
Numbers diagnosed have increased by over 70% since 2004-05, and are projected to reach 100,000 by 2020.
Mr Donnelly added: "The projected growth of Type 2 diabetes creates a real risk that the current model of care provision will become unsustainable."
He said the current strategy offers potential to secure real improvements.
"However, for too long, the prevalence of the condition, the serious healthcare outcomes for people living with it, and the costs associated with treating it have been increasingly unchecked."
"I can only conclude that to date value for money has not been achieved in delivering Type 2 diabetes services."
The report made a series of findings on policy development, improving care and measuring care standards.
It said: "Whilst the need for a clinical database of local diabetes patients linking primary and secondary care was highlighted in 2003, integrated systems have still not been introduced."
The report concluded that the Department of Health faces challenges in securing the necessary funding and effectively addressing areas of greatest priority.