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Insulin

Episodes

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Q&A #52 with Dr. Rhonda Patrick (10/7/23)

Posted on October 11th 2023 (over 1 year)

Dr. Rhonda Patrick explores supplemental tyrosine, lion's mane, cordyceps, aging tests, and sunscreen's efficacy and safety in a Q&A.

exercise

Increasing metabolism — Is high-intensity interval training better? | Dr. Martin Gibala

Posted on September 28th 2023 (over 1 year)

In this clip, Dr. Martin Gibala discusses the 'afterburn effect' and its impact on post-workout metabolism.

exercise

Why 'exercise snacks' that spread out exercise benefit glucose regulation (1-minute workouts) | Dr. Martin Gibala

Posted on September 28th 2023 (over 1 year)

In this clip, Dr. Martin Gibala discusses the ongoing studies and their objectives in understanding the impact of "exercise snacks".

Topic Pages

  • Sugar-sweetened beverages (SSBs)

    Sugar-sweetened beverages such as soda, juice, and sports drinks provide large doses of rapidly absorbable sugar, posing a unique risk to health.

  • Ultra-processed Foods (UPFs)

    UPFs are formulations of mostly cheap industrial sources of dietary energy (calories) and nutrients plus additives that have negative effects on human health.

News & Publications

  • Nearly half of people with type 2 diabetes have multiple micronutrient deficiencies—the most common being vitamin D. nutrition.bmj.com
    Vitamin D Diabetes Micronutrients Magnesium Vitamin B12 Insulin Metformin

    Micronutrient deficiencies contribute to insulin resistance, a key driver of type 2 diabetes, but researchers still don’t fully understand their role in the disease’s progression. A recent study found that nearly half of people with type 2 diabetes suffer from multiple micronutrient deficiencies, with vitamin D being the most prevalent.

    Researchers analyzed data from studies investigating links between micronutrient deficiencies and type 2 diabetes. Their analysis included 132 studies and more than 52,000 participants.

    They found that 45% of people with type 2 diabetes had multiple micronutrient deficiencies. Women with the disease were more likely to have deficiencies, with 48% affected compared to 41% of men. Vitamin D deficiency was the most common, affecting 60% of participants, followed by magnesium (42%) and vitamin B12 (28%)—the latter being especially prevalent among people with type 2 diabetes who were taking metformin. The prevalence of deficiencies also varied by region.

    These findings suggest that micronutrient deficiencies are widespread in people with type 2 diabetes, particularly among women. Check out our many resources on micronutrients, including vitamin D and magnesium, and the long-term health consequences of deficiencies.

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  • Even a brief five-day junk food binge can disrupt the brain's insulin function, potentially impairing memory and influencing eating decisions over the long term. www.nature.com
    Brain Diet Insulin

    Study link:

    Indulging in a junk food binge can have lasting effects on your brain, even after you return to your usual eating habits. A recent study found that five days of overeating high-calorie, nutrient-poor foods temporarily boosted brain insulin sensitivity but caused a drop in responsiveness once participants switched back to a healthier diet.

    Researchers assigned 29 healthy-weight men, ages 19 to 27, to one of two groups: One followed a junk food diet for five days, while the other stuck to their regular eating habits. They measured participants' brain insulin activity through imaging techniques and insulin administration before and after the binge.

    At the peak of the junk food binge, researchers observed heightened insulin activity in key brain regions. However, just one week after returning to their usual diet, participants who had overindulged experienced lower brain insulin sensitivity, particularly in areas associated with memory and food-related reward, such as the hippocampus and fusiform gyrus. Interestingly, while the junk food group showed increased liver fat, there were no noticeable changes in weight or peripheral insulin sensitivity.

    These findings suggest that the effects of overeating go beyond immediate metabolic changes, potentially contributing to cognitive decline and influencing eating behaviors over time. They also underscore how even a brief junk food binge can disrupt insulin function in the brain, impairing areas critical to memory and decision-making. Behavioral strategies like mindfulness can help curb overeating. Learn more in this clip featuring Dr. Ashley Mason.

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  • Aspartame, a popular artificial sweetener, provokes a sharp increase in insulin secretion and fosters atherosclerosis in animal models, potentially elevating cardiovascular risks. https://www.cell.com/cell-metabolism/fulltext/S1550-4131\(25\)00006-3
    Diet Insulin

    Scientists have long debated whether artificial sweeteners influence insulin levels and cardiovascular risk. A recent study found that consuming aspartame, a popular artificial sweetener, sharply increased insulin secretion in mice and monkeys, a process driven by parasympathetic nervous system activation.

    Researchers fed mice a diet containing 0.15% aspartame and measured changes in blood insulin levels. They also surgically severed the vagus nerve in some animals to assess whether parasympathetic activation was involved. To examine insulin’s role in atherosclerosis, they implanted slow-release insulin pumps in mice to mimic chronically elevated insulin levels. Finally, they tested aspartame’s effects in Cynomolgus monkeys, which are metabolically similar to humans.

    They found that mice that consumed aspartame experienced a sharp increase in insulin secretion, an effect eliminated after severing the vagus nerve. Long-term aspartame consumption worsened atherosclerosis, and implanting insulin pumps had a similar effect. In monkeys, aspartame triggered an insulin spike comparable to the effects of sucrose. However, instead of raising blood sugar, it lowered it, potentially driving insulin resistance, inflammation, and increased risk of atherosclerosis. Further analysis revealed that aspartame-induced insulin secretion activated cell signaling pathways linked to arterial inflammation and plaque formation.

    These findings suggest that aspartame consumption worsens cardiovascular risk by increasing insulin secretion, altering glucose metabolism, and promoting inflammation and plaque buildup in the arteries. Notably, the aspartame dose used in the experiment greatly exceeds what most humans consume. While the study provides insight into biological effects, its relevance to typical human intake is unclear due to the high exposure levels. Learn more about artificial sweeteners and other sugar substitutes in Aliquot #66: Sugar substitutes: Risks and benefits

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  • Daily cinnamon supplementation averaging 2,100 milligrams – roughly a teaspoon – shows promise in managing type 2 diabetes. pubmed.ncbi.nlm.nih.gov
    Diet Diabetes Insulin Resistance Insulin Polyphenol

    Cinnamon is one of the most consumed spices in the world, popular in both sweet and savory dishes in many cuisines. Evidence suggests cinnamon improves lipid profiles and protects against damage induced by oxidative stress. A recent systematic review and meta-analysis found that cinnamon helps maintain healthy blood glucose levels and reduces insulin resistance in people with type 2 diabetes.

    Researchers analyzed the findings of 24 clinical trials investigating the effects of cinnamon supplementation on blood glucose levels. The various trials included more than 1,800 participants from 11 nations.

    The analysis revealed that cinnamon supplementation reduced fasting blood glucose levels, hemoglobin A1c concentrations, and insulin resistance (without lowering insulin) in people with type 2 diabetes. The trials varied in duration from six to 16 weeks, and daily cinnamon doses ranged from 120 to 6,000 milligrams, averaging 2,100 milligrams – roughly a teaspoon.

    These findings suggest that cinnamon improves symptoms of type 2 diabetes and may be a valuable adjunct to traditional therapies. Cinnamon is rich in polyphenols, a broad class of plant bioactive compounds. Learn more about polyphenols in our overview article.

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  • Supplemental vitamin K2 improves diabetes markers and glycemic control. pubmed.ncbi.nlm.nih.gov
    Metabolism Diabetes Insulin Resistance Vitamin K Insulin

    Vitamin K2 – a form of vitamin K produced in the gut – plays important roles in blood clotting, bone mass maintenance, and blood vessel contractility. But new research shows that supplemental vitamin K2 also improves diabetes markers. People with type 2 diabetes who took supplemental vitamin K2 had better markers of glycemic control than those who took a placebo.

    Researchers performed a three-part study in humans and mice. First, they conducted a randomized controlled trial involving 60 adults who had type 2 diabetes. Half of the participants took vitamin K2 every day for six months, while the other half took a placebo. Then the researchers transplanted gut microbes from vitamin K2-supplemented mice into obese mice. Finally, they analyzed the gut microbial composition and their metabolites in both humans and mice.

    They found that the participants who received supplemental vitamin K2 experienced marked reductions in levels of fasting blood glucose (13.4 percent), insulin (28.3 percent), and HbA1c (7.4 percent), indicating improved glycemic control. Similarly, the mice demonstrated improved glucose tolerance after receiving the gut microbe transplants. Lastly, the researchers found that certain metabolites that play roles in glucose metabolism, including bile acids and short-chain fatty acids, increased in the feces of both groups. Furthermore, they identified a specific type of bacteria that was responsible for producing these metabolites.

    Vitamin K is a fat-soluble vitamin. The body has limited vitamin K storage capacity, so the body recycles it in a vitamin K redox cycle and reuses it multiple times. Naturally occurring forms of vitamin K include phylloquinone (vitamin K1) and a family of molecules called menaquinones (vitamin K2). Vitamin K1 is synthesized by plants and is the major form found in the diet. Vitamin K2 molecules are synthesized by the gut microbiota and found in fermented foods and some animal products (especially liver).

    These findings suggest that vitamin K2 participates in maintaining glycemic control in people with type 2 diabetes. They also underscore the role of the gut microbiota in this process. Learn about other roles for the gut microbiota in this episode featuring Dr. Eran Elinav.

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  • Vitamin D protects against high glucose-induced pancreatic β-cell dysfunction via AMPK- NLRP3 inflammasome pathway pubmed.ncbi.nlm.nih.gov
    Vitamin D Insulin

    Vitamin D protects pancreatic beta cells in type 2 diabetes.

    Chronic inflammation is a principal driver of many of the pathological processes that accompany type 2 diabetes, a metabolic disorder characterized by hyperglycemia (high blood glucose) and subsequent pancreatic beta cell dysfunction. Findings from a recent study suggest that vitamin D blocks activation of the NLRP3 inflammasome, preventing inflammation-driven impairment of pancreatic beta cells.

    The NLRP3 inflammasome is a large, intracellular complex that plays critical roles in immune function. Its activation triggers the release of the proinflammatory proteins interleukin (IL)-1 beta and IL-18, promoting inflammation and cell death. People who have type 2 diabetes exhibit upregulated NLRP3 inflammasome activation. However, AMP-activated protein kinase (AMPK), an enzyme that participates in metabolic regulation, blocks NLRP3 activation.

    The investigators conducted a three-part study. First, they evaluated the vitamin D status of 399 adults with type 2 diabetes and 78 healthy adults. There was no significant difference in vitamin D status between the two groups. Although males tended to have higher vitamin D concentrations than females, vitamin D deficiency was common among both sexes, with approximately 80 percent of males deficient and 91 percent of females deficient. The investigators then assessed the participants' beta cell function following a meal. They found that higher vitamin D concentrations were associated with greater beta cell function, but this correlation was seen in males only.

    In a second experiment, the investigators fed rats either a normal diet or a high-glucose diet (designed to induce beta cell dysfunction) for five weeks. They supplemented half of the rats in both diet groups with vitamin D. At the end of five weeks, they found that among rats that ate the high-glucose diet, those that received vitamin D had lower blood glucose levels than those that did not. The rats that received vitamin D also had greater insulin secretion – an indicator of healthy beta cell function.

    Finally, they conducted an in vitro experiment to evaluate the effects of vitamin D on INS1e cells, a well-established model for studies of pancreatic islet beta cell function. They found that vitamin D inhibited hyperglycemia-induced NLRP3 activation and IL-1 beta production, leading to lower levels of inflammation. Further investigation revealed that vitamin D upregulated AMPK production in the cells, which likely contributed to the reduction of inflammation.

    These findings suggest that vitamin D inhibits NLRP3 activation via enhanced AMPK production, thereby reducing inflammation due to high blood sugar in mice with type 2 diabetes. Learn more about the beneficial effects of vitamin D in our overview article.

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  • Insulin improves dopamine signaling in regions of the brain associated with eating behavior. www.sciencedaily.com
    Obesity Insulin Dopamine

    Insulin signaling in the brain influences behavior, weight regulation, motivation, and cognition. Previous research demonstrates that insulin resistance reduces brain volume and cognitive function in middle-aged adults. Results of a new study demonstrate that insulin interacts with dopamine to modulate reward-based behavior and whole-body metabolism.

    Dopamine is a neurotransmitter that regulates activity of the mesocorticolimbic system, a region of the brain involved in reward-based learning. Mesocorticolimbic circuits transmit information from the midbrain to the ventral and dorsal striatum, prefrontal cortex, amygdala, and hippocampus to coordinate emotions, memories, and impulses involved in eating and other rewarding behaviors. Previous research has demonstrated that insulin interacts with dopamine, altering activity of the mesocorticolimbic systems, inducing feelings of satiety and decreasing high-calorie food seeking. However, much of the existing research has been conducted in mice, using very high levels of insulin, making translation to humans difficult.

    The investigators assigned ten male participants (average age, 27 years) with a normal BMI (average BMI, 24) to receive either intranasal insulin or a placebo and undergo a combined PET and MRI scan after having fasted overnight. The researchers gave participants an injection of a radioactive marker called [11C]-raclopride that binds to dopamine receptors so they could measure dopamine-related brain activity during the scan. Participants also completed surveys to assess eating behavior and provided a blood sample for measurement of insulin and other hormones.

    Following administration of intranasal insulin, [11C]-raclopride synaptic binding potential increased in the ventral and dorsal striatum, suggesting an increase in the number of dopamine receptors in these regions. Accordingly, synaptic dopamine concentrations (dopamine that has not bound to a receptor and internalized by the neuron) decreased. Ultimately, this increase in dopamine signaling reduced resting-state activity in the ventral and dorsal striatum and improved functioning of mesocorticolimbic circuits 15 to 45 minutes after insulin exposure. As the participants' response to insulin exposure increased, so did their scores on tests of subjective wellbeing and cognitive control.

    This study, which demonstrated the effects of intranasal insulin on dopamine activity in the mesocorticolimbic system, has important implications for reward-based learning, eating behavior, and obesity. Future research should include participants with insulin resistance to gain a better understanding of the effects of obesity and metabolic disease on the brain.

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  • Allulose reduces blood sugar and insulin levels. drc.bmj.com
    Diabetes Sugar Insulin Blood Sugar

    Foods with a high glycemic index, such as sugar-sweetened soft drinks, desserts, and white bread products, contain sugars that are rapidly absorbed into the bloodstream, causing hyperglycemia (high blood glucose). Regular consumption of high glycemic foods may lead to insulin resistance, type 2 diabetes, and obesity. Low-calorie sweeteners (i.e., artificial sweeteners) such as allulose have a low glycemic index and can be used in place of sugar to reduce the intake of calories and high-glycemic carbohydrates; however, the effects of allulose in addition to sugar require further investigation. Findings published in a new report show that allulose significantly reduces glucose and insulin levels following sugar consumption.

    Allulose is a rare sugar that can be found in small amounts in some fruits and grains and is sold as a low-calorie sweetener. Allulose is an epimer of fructose, meaning its chemical structure is very similar to fructose, giving it a nearly identical taste and texture; however, allulose provides only 0.4 calories per gram, compared to 4 calories per gram of fructose. A meta-analysis of previous research found that small doses of allulose improved glucose and insulin regulation; however, additional randomized controlled trials are needed, especially in Western populations and in people without type 2 diabetes.

    The researchers recruited 30 participants (average age, 33 years) without type 2 diabetes and asked them to follow an individualized diet plan that provided 50 to 65 percent of calories from carbohydrates for up to eight weeks. Participants completed five study visits with one to two weeks between visits. At each visit, the researchers gave participants a beverage containing 50 grams of fructose (the amount in about 16 ounces of sugar-sweetened soda) with escalating doses of allulose (0, 2.5, 5, 7.5, or 10 grams). They measured glucose and insulin levels in the blood 0, 30, 60, 90, and 120 minutes after beverage consumption.

    Allulose consumption reduced plasma glucose levels among participants in a dose-dependent manner, meaning as the dose of allulose increased from 0 to 10 grams, glucose levels at each time point decreased. The relationship between allulose and lower glucose levels was statistically significant at the 30-minute time point when either 7.5 or 10 grams of allulose was added to the fructose beverage. Compared to consuming a fructose beverage with no added allulose, the 10-gram dose of allulose also significantly decreased insulin levels 30 minutes after beverage consumption.

    These findings demonstrate that allulose decreased glucose and insulin levels when added to a high-sugar beverage in healthy young people without diabetes. The authors suggested that future studies explore more of the mechanisms underlying these results.

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  • Alterations in gut microbial fermentation modulate the efficacy of exercise for diabetes prevention and management. www.cell.com
    Exercise Microbiome Insulin Carbohydrates

    Public health officials and healthcare providers commonly recommend exercise as a strategy to prevent or manage the symptoms of type 2 diabetes, but the cardiometabolic response to exercise is variable. Whereas exercise improves insulin sensitivity and promotes cardiovascular health in most adults (responders), exercise exerts a paradoxical effect in which metabolic health is compromised in as many as 69 percent of adults (non-responders). Findings from a recent study suggest the variable effects of exercise in people with prediabetes may be due to alterations in gut microbial fermentation.

    Microbial fermentation is the process by which gut bacteria break down and utilize carbohydrates in the gut. The metabolites produced during microbial fermentation include short-chain fatty acids and branched-chain amino acids, which are absorbed and used by the host. Short-chain fatty acids improve symptoms of diabetes, but branched-chain amino acids have the converse effect

    The study involved both humans and mice. The human study included 39 overweight or obese men with prediabetes who were between the ages of 20 and 60 years. Participants were randomized to engage in either sedentary activities or supervised exercise training for 12 weeks. They maintained their usual diet throughout the study period. At the end of the 12-week period, fecal microbial samples from two of the participants (responders and non-responders) were transplanted into obese mice.

    The results demonstrated that the responders' microbiota displayed increased production of short-chain fatty acids, whereas those of the non-responders displayed increased production of brain-chain amino acids. Fecal microbial transplantation from responders mimicked the effects of exercise on alleviation of insulin resistance in the mice, but fecal transplants from the non-responders did not. These findings may augment and facilitate clinical management of symptoms of diabetes.

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