Type 2 diabetes: A diet low in refined carbohydrates may help, say experts

Research shows carbohydrates from bright coloured plants can improve blood sugar control

"If there is one thing to take away ... it is that type 2 diabetes [T2D] can go into remission and it need not be a lifelong progressive chronic illness." That was the verdict of a 2019 report by the parliament of western Australia.

Driving this view is growing evidence from peer-reviewed studies supporting a low-carbohydrate (LC) approach to T2D management.

For example, dietitian Tara Kelly – an honorary clinical fellow at NUI Galway – is lead author of a narrative review in the International Journal of Environmental Research and Public Health, published this year. It highlights data suggesting "that adopting a LC diet is a legitimate and potentially very effective treatment option for patients with diabetes and obesity". The review further states that "international guidelines now recognise the validity and endorse the use of these diets as a therapeutic nutritional approach, in appropriate patients".

London-based Kelly trains UK doctors and dietitians on LC and low-energy approaches to T2D management, and her co-authors are consultant endocrinologist Dr Francis Finucane of Galway University Hospitals and Dr David Unwin, a Southport-based UK GP and NHS Innovator of the year 2016. Unwin and colleagues previously discovered that "adherence amongst people with T2D or glucose-intolerance to ... [an LC diet] for an average of two years resulted in significant improvements in blood pressure, weight and lipid parameters despite 'deprescribing' of 21.5 per cent of the total drugs for hypertension."


How much carbohydrate does an LC diet specify? Kelly’s review states that the threshold is usually accepted as less than 130 grams/day, equivalent to less than 26 per cent of total energy from carbohydrates: “Consumption greater than 230g per day is consistent with no restriction of carbohydrate, although we find that many of our patients with diabetes or obesity exceed several times this amount on a daily basis.”

Cork-based retired consultant histopathologist Dr Garry Lee lost three stone in five months on an LC diet: "I've kept that off for almost six years," he told The Irish Times, adding, "I'm more energetic, but significantly, after being inclined to depression for years, I'm happier and calmer in my demeanour. My mood is the big gain."

Interestingly, a recent meta-analysis states: "Carbohydrates do not have a beneficial effect on any aspect of mood; carbohydrate consumption lowers alertness within 60-minutes after consumption; [and] carbohydrates increase fatigue within 30-minutes post-consumption."

Those describing the LC approach as a modern innovation are wrong. For example, William Banting's "Letter on Corpulence, Addressed to the Public" (1864) explains: "…total abstinence from saccharine and farinaceous [starchy] matter must drain the liver of this excessive amount of glucose, and thus arrest in a similar proportion the diabetic tendency"; Kelly and colleagues cite the 1923 Dr Elliot Joslin Diabetic Diet comprising "meats, poultry, game, fish, clear soups, gelatin, eggs, butter, olive oil, coffee, tea" with around 5 per cent of calories from carbohydrates, 20 per cent from protein, and 75 per cent from fat; and the Lancet (1926) notes that "starchy carbohydrate foods rather than … fats [are] responsible for much of the alimentary type of obesity."

Prof Carel le Roux – a global influencer and consultant in metabolic medicine – is a clinician scientist at University College Dublin.

“Increasing evidence,” Prof le Roux told The Irish Times, “suggests that diets with fewer refined carbohydrates can improve T2D control. Recent trials demonstrate that when patients adopt a diet which reduces refined carbohydrate intake – especially starch – but increases carbohydrates from brightly coloured vegetables, they can improve blood sugar control, and therefore their T2D and wider metabolic health parameters. The best foods are palatable, fresh, minimally processed and nutritionally dense. Reducing sugar and starch-containing carbohydrates can improve diabetes control, promoting sustained weight loss and less medication for patients.

“T2D is seen as a treatable disease which can be put into remission through diet, medication and bariatric surgery. But patients must have correct information and understand that diabetes remission means that the disease can return if a patient stops the intervention that caused the remission.”

App management

Last year, American researchers reported their comparison of a continuous care intervention (CCI) on 262 patients with T2D and 87 T2D patients who received the usual care (UC). Central to the CCI was a web-based software app, providing telemedicine communication, online resources and biomarker tracking tools. After two years, improvements in the CCI group included better blood glucose, weight, liver function and inflammation, and "[T]he CCI group also had a higher prevalence of diabetes reversal and remission compared to the UC group ...".

A European example of digital technology in T2D management is Gro Health, an LC approach to T2D remission. Diabetes Digital Media (DDM), Gro Health's creators, is a UK-based commercial organisation, and the app recently launched in Ireland, providing an evidence-based education programme for people with pre-diabetes, type 2 diabetes and obesity. Its roll-out is led by Tara Kelly – DDM's lead dietitian – and Bristol-based GP Dr Peter Foley from Leighlinbridge, Co Carlow, who is DDM's medical officer. In England, patients can get the app for free by prescription from their NHS GP. The same might happen in Ireland, but at present a monthly subscription is €14.99 and an annual subscription is €99.

For those patients with obesity, pre-diabetes and diabetes considering an LC approach, Dr Foley advises: “If you take medication, consult your healthcare provider about possible medication adjustments before starting an LC diet. LC confers health benefits like sustainable weight loss, lower blood glucose concentrations and improved insulin sensitivity, reducing medication for many.”

Commenting on this development, Pauline Dunne – senior dietitian and regional development officer with Diabetes Ireland – says, "We support the Gro Health approach in T2D management, but one approach doesn't fit all. Individuals should be counselled on their specific needs, preferences and priorities, with advice tailored to the person. The LC approach is one of many outlined in the 2019 American Diabetes Association 'Diabetes Care' Nutrition Consensus Statement Type 2 Diabetes and Pre-diabetes."

An LC approach may have an important role to play in both managing T2D and in challenging the perception that T2D is lifelong and progressive.