Author: Ben Dugdale

The pandemic has provided healthcare professionals with a unique opportunity to make the most of a digital approach to diabetes care.

The last year has seen dramatic changes in the way diabetes teams deliver care – with COVID-19 dictating a switch from traditional face-to-face appointments to remote care, backed up by the use of digital diabetes technology. This is something every diabetes healthcare professional has had to address. Therefore, when introducing a discussion on virtual and digital diabetes care at Advanced Technologies & Treatment for Diabetes, Satish Garg of the Barbara Davis Center, Colorado, argued that this was one of the most important sessions the online meeting had to offer.  He’s been publishing widely on diabetes telehealth and keeping a close eye on the data. As is well known, glucose control among people with diabetes has got worse in the USA over the past five years, as shown by data from the Type 1 Diabetes Exchange, possibly because more people with type 1 have overweight and obesity.

Maybe telemedicine, driven by the pandemic, offers an opportunity to address this?

Satish noted that all diabetes care at the UNC Diabetes Care Centre had to be transitioned to a virtual setting from March/April 2020 and this had been achieved within two weeks. “Data shows this can be managed with no adverse effects on time in range or rates of hypoglycaemia. Emergency use of continuous glucose monitoring (CGM) was authorised, which facilitated the transition.” At the Barbara Davis Diabetes Centre, CGM use is now up to 80% and he noted that time in range during the pandemic actually improved. “However, the improvement was directly related to socioeconomic status, which is unfortunate, but it was still seen in all groups.”

Newer CGM systems, like the Dexcom G7, and smart solutions like the InPen insulin pen- like pump are beginning to make an important contribution and Satish is working to standardise downloads from these systems and multiple daily injection (MDI) with connected pens. “I think CGM and MDI, with connected pens, might be the best way to manage diabetes globally – though in the USA and Europe, maybe insulin pumps are preferred – with data being shared through iCloud and apps. I do think that COVID-19 might have shown us that remote care through telehealth might be the way to reduce costs in diabetes care. Of course, I don’t know what the future is, but I hope diabetes telehealth is here to stay, as it will remove many barriers and patients can receive more equal care. We may even be able to use the digital and virtual approach to go beyond HbA1c and find new ways of managing diabetes.”

Telemedicine certainly seems to offer much in terms of paediatric type 1 diabetes care delivery, which can be taken into the post-pandemic world, according to Lori Laffel, of the Joslin Diabetes Centre. The gold standard would be to spend up to an hour with patient and family in an attempt to combat that suboptimal glucose control, which reaches its peak in adolescent years. Previous research has shown that more frequent follow-up visits may help in this respect. “Research at Joslin shows paediatric patients were offered six visits over two years on average, but 15% of these were ‘Did Not Attend’ or were cancelled – maybe because the face-to-face visit is inconvenient. But those who missed two visits did have worse HbA1c.” In this analysis, they looked at who attended the visit with the patient, and found lower HbA1c among those who had fathers in attendance. “Virtual care may encourage more contact and presence of one or more parents,” Lori said. “So telehealth is a potential way to improve care and outcomes.”

Telehealth can increase the pool of healthcare professionals involved in paediatric diabetes care and there is data from CGM and from insulin pumps – which converted very quickly, at the start of the pandemic, to remote data acquisition. With all this, there is now data showing that telehealth can increase frequency of care and this, in itself, may improve outcomes. “Virtual care itself isn’t new, because the intensive group in the Diabetes Control and Complications Trial had telephone calls. I think we need to look at the hybrid approach going forward, combining face-to-face with virtual or remote care.” Hybrid rather than 100% remote, because in paediatric diabetes care the remote approach has gaps. Personal interaction is needed to assess growth, inspect injection sites and carry out eye and foot examinations.

These limitations notwithstanding, the stats around remote care are impressive, with a big increase in mental health, educator and dietitian appointments. “We’ve done a study of over 600 patients before and after the pandemic and there was an increase from 2.7 to 3 visits per person per year. We saw an improvement in glycaemic control, with a doubling of those reaching target. Therefore, by potentially changing process of care through telehealth, we are able to change the outcomes.”

What are the hopes for post-pandemic paediatric care? “This increased frequency of visits works, so we are looking for a hybrid model with face-to-face visits twice a year, and remote [appointments] four times [a year]. But we will need to show non-inferiority and cost-effectiveness,” Lori concluded.

For more on the pandemic and diabetes care, see our series of short tutorials ‘Diabetes and COVID-19’.

The views expressed in this article are those of the author, Dr Eleanor D Kennedy.

At the American Diabetes Association (ADA) 81st Scientific Sessions, two fascinating presentations on the evolution of diabetes nutrition therapy revealed how we’ve got to where we are today.

We’ve known about the importance of nutrition in diabetes for more than a century. Melinda Maryniuk, a renowned dietitian who was previously Director of Care Programs at the Joslin Diabetes Center, looked back at diabetes diets of the past and the leading lights who played vital roles in our present-day understanding.

It was 1921 when the first doctor in the USA to specialise in diabetes, Elliott P Joslin, wrote about diabetes prevention and obesity, and Frances Stern (one of the USA’s first nutritionists) wrote presciently in 1927: ‘A consideration of the environment, racial habits and national customs is of more importance in the dietetic treatment of diabetes than in any other field of medicine.’

But the initial eating plans for people with diabetes were not what they are today. When we think of diets 50 to 100 years ago, said Melinda, weighing, measuring, precise, extremely low-carb and not individualised are some of the words that spring to mind.

They were created by nutrition leaders such as Frederick Allen, who wrote about the starvation diet. This involved one to four days alternating between coffee and whisky until the urine was free of sugar and then adding in thrice-boiled veg (to make them even lower carb) for two days and then gradually adding protein and fat.

There were also the Joslin diets – weighed diets with exact portions that were moderate in carbs at 40%. Over time, they became a little more adaptive and individualised.

Edward Tolstoi created ‘The Free Diet’. Food was neither weighed nor measured, but was self-chosen; patients were permitted to choose foods that didn’t differ from members of their family and desserts were allowed – but not over-indulgence.

Formal exchange lists to support the Exchange System came out in 1950 to address needs for standardisation, simplification and individualisation, but the term had been around for years before that.

Fascinatingly, in this centenary year of insulin’s momentous discovery, Melinda reflected on whether it was a setback to nutrition research. She highlighted a quote from a 2006 article written by obesity specialist, Dr Eric Westman: ‘The rapid adoption of insulin therapy and the hope that it would “cure” diabetes may have led to premature abandonment of earlier successful nutrition treatments.’

The 1980s to 2021

Dietitian and diabetes nutrition management specialist, Hope Warshaw, followed with a journey through the 1980s to the present day, first pointing out that diabetes nutrition therapy has been greatly impacted by factors such as changing eating style/patterns, the advent of glucose-lowering medications, diabetes technologies and growing pathophysiology knowledge.

The 1980s saw a study that led to the rethinking of how carbohydrates were viewed. It found that eating potatoes gave essentially the same response as oral glucose when they measured blood glucose and endogenous insulin; rice and corn gave much lower blood glucose responses, and bread came out between the two.

In the 1986 ADA Nutrition Position Statement, the recommendation for the percentage of calories as carbohydrates was set at the highest levels to date – at 55-60%. It also noted the importance of eating unrefined carbs containing fibre, after work that showed the beneficial effects of fibre intake on glycaemia.

In the 1990s, a glut of influential, long-term research was published, including the UK Prospective Diabetes Study (UKPDS) in 1998 and the Diabetes Control and Complications Trial (DCCT) in 1993. The DCCT Ancillary Study identified four key diet behaviours for improving glycaemic control: promptly treat hyperglycaemia, never overtreat hypoglycaemia, minimise extra snacking and adjust insulin for changes in food intake. 

She shared a 2021 quote from Linda Delahanty, one of the study’s authors: ‘In the DCCT, we learned that intensive insulin therapy alone was not sufficient to achieve glycaemic targets. We learned the role of the registered dietitian/registered dietitian nutritionist and that careful attention to diet was key to achieving glycaemic targets in intensive diabetes therapy without undue hypoglycaemia or weight gain.’

The next update to the ADA Nutrition Position statement came in 1997. A decrease in the consumption of saturated fat (less than 10%) was now included, along with the concept of considering medication to promote weight loss in tandem with nutrition management.

The advent of nutrition labelling also happened in the 1990s. Prior to 1990, information on the calorie, fat, carbohydrate and sugar content of foods was limited. When it became available on labelling, it was extremely useful for people living with diabetes. The addition of ‘added sugars’ on labels only came into effect in 2020.

In the 2000s, findings from the Diabetes Prevention Program showed that weight loss is a dominant predictor of reduced type 2 diabetes incidence and return to normoglycaemia, with a 16% reduction in risk per kilogram of weight loss. Physical activity was shown to be important in sustaining it. The 2004 ADA statement reflected this with an increased emphasis on insulin resistance and obesity, and the importance of weight loss.

The 2010s saw a leap in the continuous glucose monitoring (CGM) technology advances that have helped clinicians to assist patients in more closely understanding and managing their glycemic trends and food choices.

The updated ADA nutrition statement of 2013 added statements to the effect that there’s no ‘one-size-fits-all’ eating pattern, promoting instead a healthful eating pattern with a variety of nutrient-dense foods, maintaining pleasure of eating and limiting food choices only when indicated by scientific evidence. A far cry from the early days of diabetic diets.

Hope shared a succinct summary of where we are now from the session’s moderator, Alison Evert, manager of the Nutrition and Diabetes Education Programs at UW Medicine: ‘Evidence does not support a clear preference for any specific eating plan or macronutrient range for weight loss. A variety of eating plans are effective. Total energy intake versus macronutrient source of energy is of greatest importance. And what the person is willing to follow long-term.’

The ADA no longer publishes position statements but produced a nutrition therapy consensus report in 2019. Point two in particular takes us back to that first Frances Stern quote of 1927:

‘Address individual nutrition needs based on personal and cultural needs, literacy, numeracy, access to healthy foods, willingness and ability to make behaviour changes, and understanding a person’s barriers.’

It also included an extensive review of different eating patterns for people with diabetes, such as low fat, low carbohydrate, vegetarian/vegan, paleo, intermittent fasting, etc. However, there are four common denominators that hold without digging deeper into specific meal plans:

1. Emphasise consumption of non-starchy vegetables
2. Minimise consumption of added sugars and refined grains
3. Choose whole foods over highly processed foods
4. Replace sugar-sweetened beverages with water as often as possible

What’s on the menu for the future?
Crystal-ball predictions on which factors will impact nutrition therapy in the coming years from Hope and her colleagues include the role of the gut microbiome, the impact of mental health, epigenomics, metabolomics and nutrigenomics, and eating for a healthy planet.

The views expressed in this article are those of the author, Dr Eleanor D Kennedy.

People with type 1 diabetes have been pushing the boundaries of sporting excellence for the past 100 years. Now, thanks to technology like continuous glucose monitoring (CGM) and closed-loop, they are achieving more than ever before

Several athletes with type 1 diabetes are aiming for a medal at this summer’s Tokyo Olympics, while professional cyclists with Team Novo Nordisk continue to ride high. But how do they overcome the challenges to glycaemic control that sport and exercise pose in type 1? At this year’s Advanced Technologies and Treatment for Diabetes meeting, Dr Mike Riddell of the Muscle Health Research Centre, York University, Toronto, discussed how technology helps athletes with type 1 diabetes exercise safely and achieve sporting success.  

“Glycaemic control in sport is a major challenge, but CGM has taught us a lot and our research group is focused on how it can help support athletes. And there’ll be future advances in technology which will put more people on the podium,” he said.  

In 1926, the British physician RD Lawrence, who had type 1, discovered that aerobic exercise – tennis or rowing – made his insulin work much more effectively which, of course, can lead to hypoglycaemia. While this makes some fear exercise, and miss out on all its well-established benefits, others have taken on the challenge. Mike – who lives with type 1 himself and is a keen cyclist – cited examples including baseball player Bobby Clarke, who blazed the trail in the 1970s, long before CGM, and Olympic swimmer Gary Hall.

Technology makes it all possible

CGM, closed-loop, better insulins and glucagon have all helped make sport and exercise safer and pushed athletes to higher performance levels, by addressing the great glucose variability that exercise can bring. “We’re starting to understand the relationship between time in range and performance and we are now testing several closed-loop systems in exercise mode to see if we can protect athletes from hypo- or hyperglycaemia in sporting competition,” Mike explained. “We’re also starting to incorporate some other wearables, including heart rate and sleep monitors, to see if we can better understand the physiologic demands athletes placing on themselves. We have ambitious goals for athletes with type 1 diabetes.”     

Team Novo Nordisk cyclist Sam Scott then took to the stage to talk about the day-to-day reality of pursuing his sport. CGM and cycling monitors can be used remotely to investigate non-invasively some of the challenges during elite-level cycling and retrospectively analyse the data and highlight challenges with the team doctor. This approach was used in the team’s 2019 tour of California, where seven male athletes with type 1 diabetes raced for three to six hours per day, covering a distance of 126 to 218 km with a total elevation almost 21 km – all at a top speed 50 km/h. Then there’s the logistics. “When you come on one of these tours you realise it’s kind of like a moving circus. Finish your race, back to the van, get to the next hotel, recover and get ready for next race! It’s more difficult than waking up in your own bed and doing these races.”

Team Novo Nordisk has been very successful in competing against teams without diabetes. One rider was awarded the ‘most courageous rider’ jersey, and there were Top 20 and Top 10 results, and three breakaways, over the course of the California tour. When they looked back at the CGM data, they were really pleased to see how well riders kept within target during rides and, during the seven days, there were almost no hypos. There was just one concerning issue – overnight there was a steady increase in below-target glucose for all the cyclists. “The use of CGM has really highlighted to us that we need to work on this post-exercise period to help recovery and, for safety, to avoid these night-time hypos,” Sam said.

So, CGM has been really important in working with these athletes. There are so many advantages associated with being able to see their data in real time and make short-term decisions, and going through data afterwards to learn and adjust strategies for future races and training. For instance, it helps adjust carbohydrate intake and monitor insulin needs. Meanwhile, CGM alarms are particularly useful, especially overnight for avoiding hypos.

The one drawback is the sensor time lag, which does become apparent during exercise at such high speeds and when prompt decisions about refuelling might be needed. Mike commented that this might be solved by developing different predictive algorithms built into CGMs, for when glucose might be rising or dropping during a sporting performance.

Meanwhile, from the medical side, Dr Federico Fontana, Head of Performance at Team Novo Nordisk, has been making use of all the different data streams coming from his cyclists. “We are trying to better merge training data with glucose data into a common display,” he explained. This, hopefully, will lead to better training, glucose management and control, and the ability to spot patterns and trends. They’ll be able to check out differences between race days, recovery days or training at home, using very simple displays. “The long- term aim is to develop some personalised approaches through a dashboard that can support the athlete with their personal decision-making, with the whole team supporting them in turn.”

So, after 100 years of athletes trying to compete on insulin, there have been some impressive achievements – and more to come.  “We know that some recent developments like closed-loop systems, digital pens, CGM and intermittently scanned glucose monitors have really shed light on the accomplishments of some of these athletes and their level of glycaemic control. The technology allows them to make critical on-the-minute decisions about nutrition, hydration or insulin therapy patterns and we think that emerging systems may help to further improve Time in Range in these athletes,” Mike said. “And, finally, from Team Novo Nordisk, we think that novel ways of displaying data to the athletes and the coaches might give a better glimpse on how to optimise performance in these incredible human beings.”

Recommended reading
Much of this new knowledge has been highlighted in a recent position statement on CGM and intermittent glucose monitoring by EASD/ISPAD, and endorsed by the American Diabetes Association (published in both Diabetologia and Paediatric Diabetes). This highly recommended reading sets out detailed information on when it is safe to exercise, how different types of exercise produce different glucose responses, and sets out glucose targets based on this. Access the position statement on the EASD website.

For more on this topic, see Professor Mike Riddell’s presentation in our [email protected] series, ‘Exercise and insulin: a potent synergy’.

You can also hear Mike in conversation with fellow cycling enthusiast Professor Miles Fisher in their contribution to our ‘The long and short of it’ series, ‘This sporting life’.

The views expressed in this article are those of the author, Dr Eleanor D Kennedy.

Look to the liver – for non-alcoholic fatty liver disease (NAFLD) has important links with type 2 diabetes and metabolic syndrome, and can worsen the risk of cardiovascular disease.

NAFLD is a multisystem disease that begins with fat accumulation in the liver. Once 5% or more of the liver cells contain fat, the person actually has NAFLD and they are looking at a serious health issue that is attracting increasing attention among healthcare professionals. According to Professor Chris Byrne, Southampton University, speaking at this year’s Advanced Technologies and Treatment for Diabetes meeting, NAFLD may progress to liver fibrosis, cirrhosis and liver cancer. It is also associated with an increased risk of chronic kidney disease, cardiovascular disease and type 2 diabetes. And, importantly, it is often found together with metabolic syndrome, which may provide a route into earlier diagnosis of NAFLD during routine checks; maybe something can be done before it progresses too far.

Links with type 2 diabetes

Professor Byrne describes NAFLD and type 2 diabetes as a “vicious spiral of worsening disease.” Over the last few years, she and others have published evidence that NAFLD increases the risk of type 2 diabetes more than two-fold, and the presence of type 2 diabetes then accelerates the rate of progression of NAFLD to liver fibrosis and maybe even hepatocellular carcinoma. Hence, a vicious spiral. Worse still, NAFLD also doubles the risk of cardiovascular disease and increases the risk of chronic kidney disease by 50%.

Here is some of that evidence. A meta-analysis published in 2018 and updated in 2020, covering half a million patients, showed that the presence of NAFLD doubled the risk of type 2 diabetes. This increased risk is likely driven by marked hepatic insulin resistance and increased hepatic glucose output in NAFLD.

Another study, involving paired liver biopsies separated by six years, showed that 56% of patients with type 2 diabetes and NAFLD progressed to liver fibrosis, compared with 21% of those with NAFLD but no diabetes.  This was confirmed by research based on European registry data covering 18 million individuals and showing that a history of diabetes at baseline was the strongest independent predictor of a diagnosis of cirrhosis or liver cancer.

NAFLD and cardiovascular risk

“Those people who are cynical about NAFLD being an independent risk factor for cardiovascular disease in patients who have already developed type 2 diabetes often say to me ‘well, there is co-existing type 2 diabetes in these individuals and that’s what’s driving the cardiovascular disease risk’,” said Professor Byrne. So, she addressed this question with Sarah Wild at Edinburgh University, drawing upon Scottish Diabetes Registry data, with its cohort of over 134,000 individuals. They were able to compare cardiovascular events in those with liver disease and diabetes and those with diabetes alone. This clearly showed that NAFLD is an independent risk factor for incident or recurrent cardiovascular disease (CVD).

Professor Byrne believes the link with cardiovascular disease comes from the atherogenic dyslipidaemia, involving very low-density lipoprotein particles, that occurs in the context of metabolic syndrome. “The actual mechanisms involved are very complicated and seem to involve the release of proinflammatory and prothrombotic factors as well.”

Once NAFLD has been diagnosed, the diabetes team should be very aware of the increased risk of CVD. Prof Byrne recommends using your local cardiovascular risk tool, and then doubling the score for the presence of NAFLD.  

Diagnosing NAFLD

So, hopefully, with raised awareness NAFLD will be spotted earlier and more often by both non-specialists and diabetologists. Professor Byrne thinks that, ideally, all patients with type 2 diabetes should be screened for the condition. Raised liver enzymes can be a sign, of course. And there are five easily measured features of metabolic syndrome that should set alarm bells ringing during routine tests – high blood pressure, increased triglycerides, low HDL, large waist circumference and glucose of 6 mmol/l or more. There’s usually insulin resistance and high fasting insulin too, and the above-mentioned atherogenic dyslipidaemia – so plenty to look out for.

At present, liver enzymes and metabolic syndrome markers are the mainstay of diagnosis of NAFLD and data can be fed into the established diagnostic tools ELF and FIB-4 to get a score. But what threshold score should be used to warrant further investigation by elastography – also known as Fibroscan – which assesses the degree of liver fibrosis?  “This is work in progress,” said Professor Byrne. “NICE recommends an ELF threshold of 10.5 to identify those with F3 and F4 fibrosis, but the lower grade F2 should not be ignored, so we go down to a threshold of 9. Then we find that hepatology can’t cope with all these referrals for elastography investigation, so we’ve adopted a threshold of around 10. Choose your thresholds in terms of what your local service can handle.” She added that she’s expecting elastography to find its way into more diabetes clinics in the not too distant future, which will make accurate diagnosis of NAFLD easier.

Treating – and preventing – NAFLD

So what about treatment? It’s so important to consider that cardiovascular risk. “Pioglitazone, which was licensed 20 years ago, has become the forgotten cost-effective and cardioprotective drug for type 2 diabetes,” said Professor Byrne. The good news is that randomised clinical trials have shown that pioglitazone has proven efficacy in resolving NAFLD in at least 50% of patients and it also has a well-established cardioprotective effect. Similar benefits can be had from the GLP-1 receptor agonists, with the added benefit of weight loss.  “The GLP-1 receptor agonists are going to become very popular in type 2 diabetes,” she added.  And weight loss, through diet and/or medication, is very effective at facilitating loss of liver fat (as Diabetes UK’s DiRECT trials have shown) so may help stop progression of NAFLD or even prevent it from developing in the first place.

So, there’s yet another reason to encourage weight loss in type 2 diabetes management: prevent NAFLD and you prevent so many other problems down the line.

For more on this topic enrol on our course ‘Non-alcoholic fatty liver disease’, written and presented by Professor Michael Roden.

Watch out for our forthcoming debate on screening for NAFLD between Professors Gianluca Perseghin and Ken Cusi, part of our series ‘The long and the short of it’.

The views expressed in this article are those of the author, Dr Eleanor D Kennedy.

The human microbiome, its role in diabetes and whether we can modify it with diet was the subject of two presentations at the 38th International Symposium on Diabetes and Nutrition.

As an increasing amount of research turns its attention to the human gut microbiome and its influence on disease prevention, yogurt consumption is in the spotlight.

Dr Kerstin Thriene, a postdoctoral researcher at the University Medical Center Freiburg in Germany, began by looking at previous research – for example, one study found that a higher intake of yogurt was associated with a reduced risk of type 2 diabetes, but the mechanisms are complex and were not addressed.

As a brief lesson on the human gut microbiota, she explained that it’s a complex ecosystem comprising bacteria, fungi viruses and so on, and they protect the human host from potential pathogenic colonisation. They also metabolise food components that can’t be digested by the host and produce advantageous metabolites, such as short chain fatty acids.

Recent research also supports the idea that human gut microbiota directly influence the immune system, but it’s a two-way relationship as the microbiota are dependent on our choices of food, lifestyle and medications.

Problems arise when the balance is disrupted (known as dysbiosis) and this is associated with inflammation and immune-mediated diseases. Various studies have suggested an altered gut microbiome composition in people with diabetes.

A recent review confirmed this dysbiosis – alterations in the gut microbiome impact on the immune system balance and it’s mediated by the production of metabolites from gut microbiota, such as short chain fatty acids.

A difference is also seen in the microbiota between type 1 and type 2 diabetes. There are quite a few studies, said Dr Thriene, that look at the influence of diet on type 2 diabetes and the microbiome, but the microbiota also play a role in the development of type 1 diabetes.

In type 1, the dysbiosis may occur very early in life, having a strong effect on the immune system and inflammation, even before onset of the actual disease. The suggestion is that establishing a healthy microbiota as early in life as possible may prevent the initiation and progression of type 1 diabetes. However, she said, it’s not yet clear whether this dysbiosis is a consequence of the disease phenotype or whether it’s actually involved in the pathophysiology.

Obesity is also often accompanied by chronic, low-grade inflammation and some studies show that obesity-related dysregulation of the gut microbiota is connected with impaired gut-barrier function. In a recent study, it was found that the microbiota impairs insulin clearance in obese mice and may therefore play a key role in obesity and diseases such as type 2 diabetes.

We may be able to influence the composition of the microbiota with diet and this is where yogurt comes in. So far, there are very few human intervention studies looking at whether yogurt consumption can play a role. The small number that have are promising and Dr Thriene is involved in an ongoing trial investigating the effects of yogurt consumption on the human gut microbiota in 100 healthy participants, using metagenomics and metabolomics analysis to unpick its effects.

While it’s a promising area, she sounded a warning on the huge number of products promising ‘good’ or ‘healthy’ bacteria, drawing from the NHS guidance on probiotics. It states that because of the way probiotics are regulated, we can’t always be sure that the product actually contains the bacteria, that it contains enough of it to have an effect and that the bacteria are able to survive long enough to reach the gut.

She concluded that if the effects of yogurt consumption appear to be positive, the gut microbiota might function as a mediator of the health benefits derived from yogurt consumption, but that the effects of yogurt consumption on human gut microbiota is not completely clear.

The case for casein

Yogurt and the microbiome were also covered by Dr André Marette from Laval University in Canada, who discussed the impact of dairy products on the development of type 2 diabetes. (He declared conflicts of interest in that some work presented was funded by the Dairy Producers of Canada and Danone Nutricia Research.)

Studies looking at diet and type 2 diabetes tend to focus on fats and carbohydrates, but we know much less about proteins and whether they protect from type 2 diabetes. In addition, most animal-model studies looking at protein only use casein and this is far from representative of the human diet, which contains many types of protein.

Dr Marette highlighted one study that evaluated casein versus other protein types typical in a human diet – such as eggs, meat and fish – on weight gain, metabolic health and gut microbiota in an obese mouse model.

The mice were either on a high-fat, high-sucrose diet (HFHS) or a low-fat, low-sucrose diet with each of the proteins added in (so four groups). It found that casein is protective against developing full-blown metabolic syndrome in the HFHS mice compared to a mix of different protein types, and the protein source modulates gut microbiota independent of dietary fat and carbohydrate. Casein, they concluded, is a key dairy protein that reduces the risk of type 2 diabetes compared with a mix of proteins in the human diet.

Yogurt is rich in casein and he drew attention to a systematic review that showed that yogurt is the dairy product most favourably associated with a reduction in incidence of type 2 diabetes.

The next study he highlighted looked at the effects of yogurt intake on whole-body and tissue-specific insulin resistance in a new mouse model of diet-induced obesity and type 2 diabetes, and the potential role of gut microbiota and specific metabolites in yogurt’s health effects.

The yogurt dosage was the equivalent to one serving per day for humans. It showed that yogurt improves body weight and reduces energy intake. The effect was more striking in its finding that yogurt intake improves insulin resistance. When looking at the effect on the microbiota, part of yogurt’s effect on insulin sensitivity appears to be related to the change in the gut microbiome.

When looking at liver metabolomic analyses, it shows that yogurt intake increases levels of branched chain hydroxy acids (BCHA) in plasma and metabolic tissues of HFHS-fed obese mice, and BCHA plasma levels correlate with metabolic benefits of yogurt treatment in obese mice and modulate hepatic glucose production. This suggests that the gut microbiota and fermentation-derived BCHA mediate the health benefits of yogurt consumption in obese mice. This study has been submitted for publication.

For more on the metabolic syndrome, enrol on our course ‘Insulin resistance’, written and presented by Professor Kåre Birkeland.

The views expressed in this article are those of the author, Dr Eleanor D Kennedy.