Acute hospitals are overstretched while some people are waiting over a year for an outpatient appointment
The shortage of dietitians in both hospitals and the community has been described as 'grave' by Diabetes Ireland.
The Coeliac Society also says its aware of members waiting up to 14 months to be seen by a dietitian.
The autoimmune condition is solely treated by diet and "people who are not on a full, gluten-free diet have more miscarriages, more still-births, migraine, depression, they get more osteoporosis and there's higher rates of bowel cancer; so this is really serious."
It follows a recent report by the Irish Society for Clinical Nutrition and Metabolism and University College Cork.
It revealed a third of cancer patients experiencing weight loss were not being seen by a dietitian or provided with nutritional support. This is despite the impact of cachexia on survival rates.
A source has told Newstalk many hospital dietitians are so overstretched, they can only deal with the most extreme cases.
"Most dietetic departments at the minute refuse to see inpatients for management of obesity, even if they are in with a heart attack, due to having to prioritise the urgent cases"
Dr. Anna Clarke from Diabetes Ireland says the HSE's own research shows a 74% deficit of dietitians in acute diabetes settings nationally, while Limerick fares the worst with a 100% deficit.
"That means no public patient with diabetes in Limerick has access to a dietitian. They have to seek a private consult elsewhere."
Meanwhile community dietitians who work in places like Primary Care, nursing homes and disability services are also struggling to cope with demand.
There are 900 dietitians registered with CORU - the national registration board. Dietitians are qualified healthcare professionals who diagnose and treat nutritional problems.
The HSE says 600 work in the health service and 135 of those are in the community setting.
The health authority has acknowledged there are gaps in services and a need to recruit more. A spokesperson has told Newstalk:
"In 2018, a National Review of Community Dietetics was completed by the HSE, and is currently under consideration by leadership. The review outlines the current resources, gaps in access to services in community and proposed model for service delivery into the future. It is recognised that we require a significant increase in numbers. As with other services, we endeavour to ensure that adequate cover is provided when staff are on maternity leave- but this differs across hospitals and community settings."
The Irish Nutrition and Dietetic Institute calculates 400 are needed to meet the aims of HSE's own strategy documents.
Communications Manager and registered dietitian, Louise Reynolds, has told The Pat Kenny Show it would bring us up to a standard where people could access a dietitian in the community.
"It would be very aspirational but anything working towards that is going to improve the services for patients. There were 18 specialised diabetes dietitians recently appointed in the community, there are dietitians working with cancer, but throughout the system there are so many more needed."
The profession is dominated by women and female dietitians taking maternity leave are not always replaced. The INDI says there's usually a 20% vacancy rate.
Dietitian Sarah Keogh with the Coeliac Society says an increased investment in this area would save the health service in the long run.
"There's really good evidence that we can put Type 2 diabetes into remission with diet treatment. There's also heart disease, blood pressure, cholesterol level, weight management, obesity and risk of malnutrition... if we could improve nutrition we would see fewer people attending A&E and fewer beds occupied in hospitals for long stays."
Hospital food policy
On Wednesday, the HSE announced its new Food, Nutrition and Hydration Policy for Adult Patients in Acute Hospitals.
It will involve screening patients' diets on admission to hospital and referring them to a dietitian where necessary.
Barbara Gillman, clinical specialist renal dietitian, headed up the project.
"Once their needs are assessed, they will be assigned an appropriate hospital menu, or will be referred to a dietitian for a nutritional care plan and assistance if necessary. The patient will then be screened weekly to ensure their needs continue to be met".