Study debunks belief insulin puts people with diabetes at risk of heart disease

ScienceDaily (June 11, 2012) — Researchers at McMaster University have discovered that long-term insulin use does not harm people with diabetes or pre-diabetes or put them at risk of heart attacks, strokes or cancer.

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This is contrary to concerns that long-term use of insulin may cause heart disease, says Dr. Hertzel Gerstein, principal investigator of the study, professor of medicine at McMaster's Michael G. DeGroote School of Medicine and deputy director of the Population Health Research Institute at McMaster University and Hamilton Health Sciences.

"People have been debating the question of whether there are adverse consequences to long-term insulin use for years," he said. "This study provides the clearest answer yet to that question: No, there are not."

Gerstein recently presented the findings of the ORIGIN study (Outcome Reduction with an Initial Glargine Intervention study), at the scientific sessions of the American Diabetes Association in Philadelphia. The results were also recently published in two papers in the medical journal New England Journal of Medicine (NEJM).

A second important finding of the study is that people with pre-diabetes who received daily basal insulin injections with insulin glargine had a 28 per cent lower chance of developing type 2 diabetes, even after the injections stopped.

Gerstein jointly led the study with Dr. Salim Yusuf, professor of medicine and director of the Population Health Research Institute.

Today, more than nine million Canadians are living with diabetes or pre-diabetes. Diabetes is a chronic condition, often debilitating and sometimes fatal disease, in which the body either cannot produce insulin or cannot properly use the insulin it produces. This leads to high levels of glucose in the blood which can damage organs, blood vessels and nerves. The body needs insulin to use glucose as a source of energy.

In the ORIGIN study, more than 12,500 people at 537 sites in 40 countries with an average age of 64, who are at high risk for, or in the early stages of type 2 diabetes, were randomized to either one daily injection of insulin (glargine) or no insulin (standard care) for an average of six years.

Researchers found no difference among the two groups in cardiovascular outcomes or in the development of any type of cancer. This suggests daily insulin injections (with insulin glargine) to normalize glucose levels are not harmful when taken over long periods of time. Throughout the study, most of the participants given insulin maintained normal fasting glucose levels (below 6 mmol/l).

The study confirmed the presence of two previously known side effects of insulin -- hypoglycemia (low blood sugar) and modest weight gain. Both were considered minor from a medical point of view, with participants gaining an average of 3.5 pounds during the study and experiencing a low, 0.7 per cent higher risk of severe hypoglycemia per year than the people not on insulin.

"We now know what the risks are of taking insulin on a long-term basis, and they are low," Gerstein said.

The study also discovered that daily doses of one-gram omega-3 fatty acid capsules did not prevent cardiac-related deaths in people with type 2 diabetes or prediabetes.

"There was neither benefit nor harm in the participants who were studied," said Jackie Bosch, associate professor of McMaster's School of Rehabilitation Science and project manager for the trial. "However, the effect of these supplements in other groups, and the effect of a diet rich in omega 3 fatty acids was not studied."

The study was funded by the drug company Sanofi Inc. and the omega-3 supplement was provided by Pronova Biocare AS, the Norwegian manufacturer of omega-3, and independently conducted by the Population Health Research Institute at McMaster University and Hamilton Health Sciences.

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Overfed fruit flies develop insulin resistance; Represent new tool to study human diabetes

ScienceDaily (June 5, 2012) — Researchers find that fruit flies overloading on carbs and protein not only gain weight but have shortened life spans -- and develop insulin resistance, a hallmark of Type 2 human diabetes.

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With Type 2 human diabetes climbing at alarming rates in the United States, researchers are seeking treatments for the disease, which has been linked to obesity and poor diet.

Now biologists at Southern Methodist University, Dallas, report they have developed a new tool that will help researchers better understand this deadly disease.

By manipulating the diets of healthy adult fruit flies, the researchers developed flies that are insulin-resistant, a hallmark of Type 2 diabetes.

Until now, researchers largely have relied on rats, mice and other animals as model systems for exploring the metabolic and genetic changes that take place in diabetics.

The fruit fly Drosophila melanogaster has been widely deployed in labs to investigate a wide range of human diseases, from Alzheimer's to cancer. But the scientific literature hasn't documented use of the adult fruit fly for studying the metabolic disruptions that are the hallmark of Type 2 diabetes. The fruit fly's advantages include its low cost and a very short lifespan, both of which enable scientists to undertake rapid screenings in their search for new genetic and drug treatments.

The insulin-resistant fruit fly was developed in the lab of SMU biologist Johannes H. Bauer, principal investigator for the study. It was accomplished by feeding fruit flies a diet high in nutrients, said Bauer, an assistant professor in SMU's Department of Biological Sciences. That process mimics one of the ways insulin resistance develops in humans -- overeating to the point of obesity.

The lab's insulin-resistant fruit flies now can serve as a highly relevant and efficient model for studying Type 2 diabetes.

"We learned that by manipulating the nutrients of fruit flies, we can make them insulin resistant," Bauer said. "With this insulin-resistant model we can now go in with pinpoint precision and study the molecular mechanisms of insulin resistance, as well as drug treatments for the condition, as well as how to treat obesity, how to block insulin resistance and how metabolic changes from a specific diet develop. The possibilities are endless."

The researchers reported their findings in the article "Development of diet-induced insulin resistance in adult Drosophila melanogaster," published in Biochimica et Biophysica Acta -- Molecular Basis of Disease.

Two overfeeding diets, carb and protein, both result in insulin resistance

Insulin, produced by the pancreas, is the hormone that tells our cells to absorb glucose, a necessary sugar molecule that provides our body, particularly the brain, with the energy to function, make repairs, move and grow.

In Type 2 diabetes, a person is insulin-resistant because his or her cells fail to respond to insulin's signal to absorb glucose. The disregulation of glucose upsets the body's delicate internal equilibrium, causing massive disruptions in normal cellular processes. These interruptions manifest in multiple disease symptoms, making Type 2 diabetes difficult to characterize, treat and cure.

To provide a good base model organism to study aspects of this complex disease, researchers in the Bauer lab wanted to determine whether flies develop diabetes-like metabolic changes when fed different diets. The researchers developed the insulin-resistant flies in two different ways: One group of fruit flies was overfed a carbohydrate-loaded diet; a second group of flies was overfed a protein-loaded diet. In both cases, the disruption had a profoundly detrimental effect on the flies' health and physiology.

SMU biologist Siti Nur Sarah Morris, lead author on the study, said the results the researchers observed were both expected and unexpected. The researchers expected the flies to gain weight, which they did. Carb-loaded flies gained excessive weight and got fat, just like humans who overeat sweets, french fries, pasta and ice cream. Protein-loaded flies also gained weight, but upon extreme overfeeding they lost weight, just like humans who follow the popular Atkins Diet, a weight loss program in which participants eat only meat, seafood and eggs.

The researchers expected the carb-loaded fruit flies to develop insulin resistance, which they did.

In a surprising result, however, the fruit flies that overate protein also developed insulin resistance, but at a quicker and more severe rate.

"Carb-loaded flies gain weight. Protein-loaded flies gain and then lose weight. So the two diets have exactly opposite effects on metabolism," Bauer said. "But too much of either one of them causes insulin resistance. That surprised us."

Overfed flies had shortened lifespans, differences in fertility

In other findings, carb-loaded flies experienced a profound decline in egg-laying, a measurement of fertility. In contrast, protein-loaded flies first experienced increased egg-laying, but the extreme diet led to decreased egg laying. Both diets led to shortened longevity, the scientists reported.

"The high-protein flies looked frail and unhealthy. They moved less, almost as if sedated," Morris said. "The fatter flies on the high-carb diet had massively decreased fertility; they flew less but still tried to move."

While both diets resulted in insulin resistance, differences were remarkable.

"The carb data imply a linear relationship between carb levels and health. The more carbs, the more weight, the more sugar storage and fat, the more insulin resistance and the less fertility," Bauer said. "But with protein, this relationship becomes parabolic, meaning all readouts go up, then come down again. The decreased storage we liken to a catabolic state that is primarily destructive for the body's optimum metabolic functioning, such as the ketosis typically seen in people eating Atkins-type diets."

Besides Morris and Bauer, other authors on the study were SMU students Claire Coogan, Khalil Chamseddin and Santharam Kolli. Other co-authors, from Pennington Biomedical Research Center, Baton Rouge, La., are Jeffrey N. Keller, director, Institute of Dementia Research & Prevention, and Sun Ok Fernandez-Kim. The research was funded by the National Institute on Aging.

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Increased bodyweight after stopping smoking may be due to changes in insulin secretion

ScienceDaily (May 7, 2012) — Fear of putting on weight is one of the major reasons why smokers do not give up their habit. The reasons for this weight gain are believed to be in part due to metabolic changes in the body, but until now precise details of these changes were not known. On May 8, 2012, however, a researcher from Austria told delegates at the International Congress of Endocrinology/European Congress of Endocrinology that her work had shown that changes in insulin secretion could be related to weight gain after smoking cessation.

See Also:Health & MedicineSmokingDiet and Weight LossDiabetesObesityFitnessHormone DisordersReferenceBlood sugarDiabetes mellitus type 2HyperglycemiaGlycemic index

Dr. Marietta Stadler, from the Hietzing Hospital in Vienna, Austria, enrolled healthy smokers on a smoking cessation programme into a study in which they underwent three-hour oral glucose tolerance tests (OGTT) while still smoking and after a minimum of three and six months after giving up. Their body composition was also measured at the same time. The researchers measured beta cell

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