LOS ANGELES – More than 20 years ago, Roy Taylor, MD, began working to further understand the pathogenesis of hepatic insulin resistance in people with type 2 diabetes. It became clear that the main determinant was the amount of fat in the liver.
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“If you reduced the amount of fat, the resistance went down,” Dr. Taylor, professor of medicine and metabolism at Newcastle University (England), said at the annual scientific and clinical congress of the American Association of Clinical Endocrinologists. “We had a very clear picture of what might be controlling this awful matter of fasting glucose being too high.”
Then, Dr. Taylor read a study from Caterina Guidone, MD, and colleagues in Italy, which found that 1 week after patients with type 2 diabetes underwent gastric bypass surgery, their fasting plasma glucose levels became normal (Diabetes. 2006;55[7]:2025-31). “I was sitting at my desk and I thought, ‘This really changes type 2 diabetes,’ ” Dr. Taylor said. “It set in process a series of thoughts as to what was controlling what.”
This inspired ongoing work that Dr. Taylor termed the “twin-cycle hypothesis,” which postulates that chronic calorie excess leads to accumulation of liver fat, which spills over into the pancreas (Diabetologia. 2008;51[10]:1781-9).
“People with type 2 diabetes have been in positive calorie balance for a number of years,” he said. “That’s going to lead to an excess of fat in the body, and liver fat levels tend to rise with increasing body weight. If a person has normal insulin sensitivity in muscle tissue, then dealing with a meal is quite easy. Some 30 years ago, we showed using MR spectroscopy that you will have stored the carbohydrate from your breakfast in muscle, to the extent of about one-third of your breakfast, and the peak will be about 5 hours after breakfast. If you had your corn flakes at seven in the morning, by noon there will be peak in muscle, nicely stored away. However, if you happen to be insulin resistant in muscle, that doesn’t happen. There’s only one other pathway that the body can use, and that’s lipogenesis. The body can turn this very toxic substance [glucose] into safe storage [fat]. A lot of that happens in the liver. This means that people with insulin resistance tend to build up liver fat more rapidly than others.”
To test the twin-cycle hypothesis, Dr. Taylor and colleagues launched an 8-week study known as Counterpoint, which set out to induce negative calorie balance using a very low–calorie diet – about one-quarter of an average person’s daily food intake – in 11 people with diabetes (Diabetologia. 2011;54[10]:2506-14). The diet included consuming three packets of liquid formula food each day (46.4% carbohydrate, 32.5% protein, and 20.1% fat; plus vitamins, minerals, and trace elements), supplemented with portions of nonstarchy vegetables such that total energy intake was about 700 calories a day.
“On a liquid-formula diet, hunger is not a problem after the first 36 hours,” Dr. Taylor said. “This is one of the best-kept secrets of the obesity field. Our low-calorie diet was designed as something that people would be able to do in real life. We included nonstarchy vegetables to keep the bowels happy. That was important. It also fulfilled another point. People didn’t want just a liquid diet. They missed the sensation of chewing.”
The researchers also developed three-point Dixon MRI to measure pancreas and liver triacylglycerol content. “The pancreas was particularly challenging, and the full resources of the magnetic resonance physics team were needed to crack the technical problems,” he said.
After just 1 week of restricted energy intake, the fasting plasma glucose level normalized in the diabetic group, going from 9.2 to 5.9 mmol/L (P = .003), while insulin suppression of hepatic glucose output improved from 43% to 74 % (P = .003). By week 8, pancreatic triacylglycerol decreased from 8.0% to 1.1% (P = .03), and hepatic triacylglycerol content fell from 12.8% to 2.9% (P = .003).
“Within 7 days, there was a 30% drop in liver fat, and hepatic insulin resistance had disappeared,” Dr. Taylor said. “This is not a significant change – it’s a disappearance. For one individual, the amount of fat in the liver decreased from 36% to 2%. In fact, 2% [fat in the liver] was the average in the whole group. But what was simply amazing was the change in first-phase insulin response. It gradually increased throughout the 8 weeks of the study to become similar to the normal control group. We knew right away that a low-calorie diet would start correcting this central abnormality of type 2 diabetes.”
After the results from Counterpoint were published, Dr. Taylor received a “tsunami” of emails from researchers and from members of the public. “Some of the medical experts said it was a flash in the pan – interesting, but not relevant,” he said. “People with diabetes learned of it by the media, and it was talked about as a crash diet, which is unfortunate. First, it wasn’t a crash diet. This diet has to be very carefully planned, and people need to think about it in advance. They need to talk about it with their nearest and dearest, because it’s the spouse, the partner, the friends who will be supporting the individual through this journey. That’s critically important. People don’t eat as isolated individuals, they often eat as a family. We’re not talking about cure. We’re talking about reversal of the processes underpinning diabetes, with the aim of achieving remission.”
Dr. Taylor created a website devoted to providing information for clinicians and patients about the low-calorie diet and other tips on how to reverse type 2 diabetes. Soon afterward, he started to receive emails from people telling him about their experiences with the diet. “In the comfort of their own kitchens these people had lost the same amount of weight as in our trial subjects – about 33 pounds,” Dr. Taylor said. “Most of them had gotten rid of their type 2 diabetes. This was not something artificial as part of a research project. This was something that real people would do if the motivation was strong enough.”
To find out if the results from the Counterpoint study were sustainable, Dr. Taylor and his associates launched the Counterbalance study in 30 patients with type 2 diabetes who had a positive calorie imbalance and whom the researchers followed for 6 months. The 8-week diet consisted of consuming three packets of liquid formula a day comprising 43.0% carbohydrates, 34.0% protein, and 19.5% fat, as well as up to 240 g of nonstarchy vegetables (Diabetes Care. 2016;39[5]:808-15). “This was followed for a 6-month period of normal eating: Eating whatever foods they liked but in quantities to keep their weight steady,” Dr. Taylor explained. “These people gained no weight over the 6-month follow-up period. They achieved normalization of liver fat, and it remained normal.”
The patients’ hemoglobin A1c levels fell from an average of 7.1% at baseline to less than 6.0%, and stayed at less than 6.0%. Patients who didn’t respond tended to have a longer duration of diabetes. Their beta cells had fallen to a level beyond that capable of recovery. “So the durability of the return to normal metabolic function was not in question, at least up to 6 months,” he said. “This study also gave us the opportunity to look at changes in pancreas fat. Was it likely that the liver fat was driving the pancreas fat? Yes.”
During the weight-loss period, the researchers found that there was the same degree of reduction of pancreas fat in the Counterbalance study as there’d been in the Counterpoint study. “Remarkably, it decreased slightly during the 6 months of follow-up,” Dr. Taylor said. “Those changes were significant. Type 2 diabetes seems to be caused by about a half a gram of fat within the cells of the pancreas.”
To investigate if a very low–calorie diet could be used as a routine treatment for type 2 diabetes, Dr. Taylor collaborated with his colleague, Mike Lean, MD, in launching the randomized controlled Diabetes Remission Clinical Trial (DiRECT) at 49 primary care practices in the United Kingdom (Diabetologia. 2018;61[3]:589-98). In all, 298 patients were randomized to either best-practice diabetes care alone (control arm) or with an additional evidence-based weight-management program (intervention arm). Remission was defined as having a hemoglobin A1c level of less than 6.5% for at least 2 months without receiving glucose-lowering therapy.
At 1 year, 46% of patients in the intervention arm achieved remission, compared with 4% in the control arm (Lancet Diabetes Endocrinol. 2019;7[5]:344-55). At 2 years, 36% of patients in the intervention arm achieved remission, compared with 2% in the control arm. “The most common comment from study participants was, ‘I feel 10 years younger,’ ” Dr. Taylor said. “That’s important.”
The percentage of patients who achieved remission was 5% in those who lost less than 11 lb (5 kg), 29% in those who lost between 11 lb and 22 lb (5-10 kg), 60% in those who lost between 22 lb and 33 lb (10-15 kg), and 70% in those who lost 33 lb (15 kg) or more.
The researchers found that 62 patients achieved no remission at 12 or 24 months, 15 achieved remission at 12 but not at 24 months, and 48 achieved remission at 12 and 24 months. “We haven’t got this perfectly right yet,” Dr. Taylor said. “There is more work to do in understanding how to achieve prevention of weight gain, maybe with behavioral interventions and/or other agents such as [glucagonlike peptide–1] agonists. This is the start of a story, not the end of it.”
He and his associates also observed that delivery of fat from the liver to the rest of the body was increased in study participants who relapsed. “What effect did that have on the pancreas fat? The people who continued to be free of diabetes showed a slight fall in pancreatic fat between 5 and 24 months,” Dr. Taylor said. “In sharp contrast, the relapsers had a complete increase. Over the whole period of the study, the relapsers had not changed from baseline. It appears beyond reasonable doubt that excess pancreas fat seems to be driving the beta-cell problem underlying type 2 diabetes.”
Dr. Taylor reported that he has received lecture fees from Novartis, Lilly, and Janssen. He has also been an advisory board member for Wilmington Healthcare.