"Again I call on the DHB to provide patients with proper evidence to support its decisions to axe the service.
"The DHB has consistently refused to provide any evidence to support its decision. If that's not giving the public the full facts, I don't know what is."
Mr Lowe had offered to fund an independent review to compare the cost of the GPSI service to the DHB service, but the health board declined.
Put Patients First said Dr Titchener's service directly reached about 10 per cent of the 8000 people with diabetes in Hawke's Bay and hundreds more through training and support.
The lobby group said they will continue to advocate for Hawke's Bay residents suffering from diabetes, helping them receive the best possible care available.
Community group, Diabetes Hawke's Bay has also come out and supported the campaign for continued DHB funding of the GPSI Diabetes Service.
Community Diabetes Educator and registered nurse Tanya Jeffcoat said the organisation was "very disturbed" the money would discontinue. "We are supportive of all services that are shown to provide such effective outcomes, of which the GPSI is one.
"Their unique approach and the intensive support of their patients and health care providers has seen positive and life-changing, even possible life-saving outcomes for both patients and their families."
Diabetes Hawke's Bay is a community organisation providing free information, support and education to people and families with pre-diabetes and diabetes.
"We have seen many people over the years who are struggling with their diabetes and have encouraged them to see Janet," Ms Jeffcoat said. "This service is too important to lose." She said because the DHB is not disputing the effectiveness of the service, their decision appears to be based solely on running costs.
"We surmise, however, the savings to the DHB through less GP, specialists and hospital visits, and less hospital stays for people going through the GPSI service outweighs the cost of funding the service."
Ms Jeffcoat expected the DHB to consult with the community, health services and hundreds of people who had been helped through the GPSI service, to enable them to make an informed decision about the cost benefit of the service.