According to Diabetes UK, around 200,000 people are diagnosed with type 2 diabetes every year and there are 3.5 million people in England with a diagnosis. The increasing number of people with type 2 diabetes is a challenge to the NHS and healthcare systems across the world. It is a leading cause of sight loss and lower limb amputation, and can contribute to kidney failure, heart attack and stroke. Diabetes and its complications cost over £6 billion every year to treat and one in six patients in hospital now has diabetes.1
Diabetes is defined at a certain level of raised blood glucose but there is no magical level at which raised blood sugar suddenly becomes harmful. There are known risks associated with raised insulin and raised glucose considerably lower than the levels defined as diabetes. In this blog we provide an overview of the hormone insulin and how dysregulation of insulin can manifest in various ways. Approaches to lower excess insulin levels are also suggested.
What is insulin?
Insulin is a hormone secreted by the beta cells in the pancreas that helps the body to use glucose from carbohydrates in food or to store it for future use. In order for this to occur, insulin attaches to cell receptors which results in glucose being taken up into the cell from the bloodstream. Insulin may be described as a “key” that unlocks the cell to allow glucose to enter and be used for energy. Thus insulin helps keep the blood sugar level from getting too high (hyperglycaemia). Dysregulation of insulin can manifest in various ways:
This term is often used to describe blood glucose levels that are higher than normal, but not high enough to be diagnosed with type 2 diabetes. It is often based on a measurement of glycated haemoglobin (HbA1c). Glucose in the blood attaches to haemoglobin and the rate at which this occurs is directly proportional to the amount of glucose in the blood. Red blood cells have a life-span of approximately two to three months so HbA1c provides an average measure of blood glucose levels over the previous three months.
The American Diabetes Association has set the level for prediabetes as a blood glucose measurement of HbA1C 5.7% (39mmol/mol). Diabetes.co.uk suggests that prediabetes is an HbA1c of 6.0 to 6.4% (or 42 to 47 mmol/mol).
Between 5% and 10% of people with prediabetes go on to develop type 2 diabetes each year.2 Plus some of the damage that occurs with diabetes may also occur with prediabetes.
Insulin resistance occurs when insulin receptors on cells in the muscles, fat and liver are constantly exposed to high levels of insulin and as a result they downregulate and do not respond normally to insulin. This leads to the pancreas releasing more insulin resulting in high levels of insulin to help glucose enter the cells; and the development of a vicious cycle as blood glucose rises, then insulin levels rise further leading to more stimulation and then more resistance etc. As well as the damage from high blood sugar, persistently high insulin itself can have a number of negative effects on the body.
Over time the beta cells in the pancreas that produce insulin become worn out and can no longer keep pace with the demand for more insulin. Blood sugar increases and pre-diabetes or type 2 diabetes may develop.
A growing problem associated with insulin resistance is non-alcoholic fatty liver disease (NAFLD). Twenty to thirty per cent of adults in the general population in Western countries have NAFLD and this increases the risk for fibrosis and cirrhosis of the liver, liver cancer, and heart disease; with prevalence as high as seventy to ninety per cent of people who are obese or who have diabetes.3,4
Insulin resistance also increases the risk for a host of other serious health problems such as cardiovascular disease,5 stroke6 and cancer.7
Metabolic syndrome is a term used to describe a collection of disorders that increase the likelihood of developing heart disease, diabetes, stroke, fatty liver, polycystic ovary syndrome and gallstones. The signs and disorders associated with metabolic syndrome are:
- Increased blood pressure that is consistently 140/90mmHg or higher
- Insulin resistance and high blood glucose.
- Excess fat around the middle – a waist circumference of 94cm (37 inches) or more in European men, or 90cm (35.5 inches) or more in South Asian men. A waist circumference of 80cm (31.5 inches) or more in European and South Asian women.
- High triglyceride levels (fat in the blood).
- Low levels of HDL cholesterol (i.e. “good” cholesterol).
- Systemic inflammation.
- Tendency to form blood clots.
Of these, the two most important risk factors for developing other conditions associated with metabolic syndrome are defined by the National Heart, Lung, and Blood Institute8 as:
- Central obesity, or excess fat around the middle and upper parts of the body
- Insulin resistance
Insulin and prostate cancer
A study in 2009 found that elevated insulin levels may be linked with an increased risk of prostate cancer. The researchers measured the relationship of serum insulin and glucose with the development of prostate cancer and found a strong association between men with high insulin levels with the development of prostate cancer.9
Insulin and breast cancer
In 2009 Albert Einstein College of Medicine published their research “High Insulin Levels Raise Risk of Breast Cancer in Postmenopausal Women”. Although a link between obesity and breast cancer had already been shown, scientists believed that the causative factor was increased levels of oestrogen in obese women. The 2009 research identified the role of increased amounts of insulin, also commonly found in obese women, in stimulating the growth of breast cancer cells in tissue cultures.10 Another study demonstrated that insulin resistance was associated with increased risk of breast cancer, ovarian cancer and endometrial cancer.11
Signs and symptoms of chronically elevated insulin levels
In addition to the signs associated with metabolic syndrome listed above, other signs and symptoms indicating a chronic elevation of insulin levels include:
- Hunger and cravings for sugar or carbohydrate rich foods –people with high blood insulin are hungry and frequently ‘crave’ carbohydrate rich foods.
- ‘Acanthosis nigricans’ – the development of brownish and dry areas of skin particularly around the neck.
- Fluid retention – insulin resistance can cause the kidneys to hang on to sodium and water, giving a puffy/bloated appearance.
- Poor skin – insulin resistance can promote higher levels of the male hormone testosterone and ongoing symptoms such as acne, large facial pores and greasy skin can occur.
- Polycystic ovary syndrome.
- In women, scalp hair loss to the front and sides.
Ways to lower excess insulin levels
There are five key steps, each of which has a synergistic effect in lowering insulin resistance – diet, exercise, stress reduction, sleep and the use of specific nutrients:
- Lower Carbohydrate Intake – carbohydrate has a much more significant impact on increasing insulin than eating fat does. Fat ingestion has a minimal effect on insulin but carbohydrate clearly increases insulin and lowering the Glycaemic Load of the diet reduces the insulin response required. Conversely, the higher the diet in refined or processed carbohydrates, the worse the level of insulin resistance. Therefore, recommendations are to:
- Avoid eating sugary or refined carbohydrates.
- Starchy carbohydrates such as wholegrains (including rice and oats) and potatoes should only be eaten in small amounts (wholemeal bread can raise blood sugar rapidly). Sweet potatoes are a better choice. In terms of portion size, starchy carbohydrates should not cover more than a ¼ of the plate at any meal.
- Consume healthy protein sources such as chicken (organic if possible), lamb/beef (1-2 x per week), wild salmon, fresh or tinned sardines (latter in olive oil), tuna tinned in spring water or olive oil, eggs, beans, lentils.
- All green vegetables/salads are recommended. Those vegetables that grow above the ground will have significantly lower carbohydrate (and higher healthful nutrients) than those that are grown below the ground.
- Be careful with fruit – all berries are great, apples and pears too, but not tropical fruits like bananas, oranges, grapes, mangoes which are especially high in sugar. Avoid tinned or dried fruit.
- Choose healthy fats such as olive oil, avocado, nuts, seeds and oily fish.
Exercise is an effective way to lower insulin resistance for two reasons. Firstly, building muscle and therefore increasing glycogen storage (by up to 20 times the amount) so that more glucose can be taken out of the bloodstream rapidly, avoiding fluctuations in blood sugar and hence spikes in insulin. Secondly, by using up glycogen stores. This happens directly while exercising but more importantly exercise boosts the overall metabolic rate by as much as ten times above resting rate and the added advantage is that the metabolic rate will remain raised for up to fifteen hours afterwards.
Stand up regularly – having a sedentary lifestyle, even if meeting the current recommendation of thirty minutes of physical activity on most days each week, leads to potentially significant adverse metabolic and health effects and is an independent risk factor for metabolic syndrome.
High Intensity Interval Training (HIIT) uses “super-fast muscle fibres” which are ten times faster than “slow fibres.” Activating super-fast fibres triggers growth hormone, which is associated with longevity and a reduction in insulin resistance.
Numerous studies show that perceived stress is an independent risk factor for developing type 2 diabetes.12,13 Persistent stress leads to chronically high levels of the hormone cortisol and this directly opposes the action of insulin leading to raised blood glucose levels. Many studies have shown that stress reduction reverses this and increases insulin sensitivity.
Chronic sleep deprivation or sleeping less than seven or eight hours per night is now recognised as a major contributor to type 2 diabetes. Lack of sleep increases insulin resistance. It also increases the hunger hormone ghrelin leading to increased calorie intake and the likelihood of being overweight or obese. In his book ‘Why We Sleep’ Mathew Walker talks about the importance of having an eight hour ‘sleep opportunity’ every night.14
Those described below are some of the options with the strongest evidence of benefit but this is by no means an exhaustive list.
Chromium is an essential mineral that appears to have a beneficial role in the regulation of insulin action and its effects on carbohydrate, protein and lipid metabolism.15,16 Chromium is reputed to reduce sugar cravings and it does this by helping to keep blood sugar stable throughout the day.17,18
Chromium increases sensitivity to insulin by increasing insulin binding to cells, increasing the number of insulin receptors on cells and activating insulin receptor enzymes. Organic forms give the best results as they are substantially more “bioavailable”. Only 1% or less of inorganic chromium is absorbed compared to 10-25% of chromium GTF (glucose tolerance factor). The latter also reduced blood glucose by 16.8% compared to 6.0% for inorganic chromium i.e. 2.8 times more effective.19
Cinnamon has been used for centuries to support normal blood glucose and has three distinct actions:
- Slowing glucose absorption from the digestive tract – it inhibits certain digestive enzymes from the pancreas and so slows down the rate of absorption of sugars from a meal
- Insulin mimetic – compounds in cinnamon mimic the effects of insulin. This means it can be particularly useful in the later stages of type 2 diabetes with pancreatic exhaustion leading to less insulin
- Improving insulin sensitivity20
Magnesium is the fourth most prevalent mineral in the body and deficiency occurs in up to 80% of the population.21 Magnesium has been shown to reduce fasting glucose and insulin resistance as insulin requires magnesium to act effectively.22,23 Importantly, magnesium entry into cells requires insulin to be acting effectively so inadequate magnesium intake prompts a vicious cycle of low magnesium levels causing insulin resistance leading to lower magnesium uptake etc.
Zinc stabilises insulin so that it binds to cell receptors more effectively.24 Zinc also acts as a co-factor for numerous enzymes in the body – including insulin degrading enzyme. IDE is required to break down insulin and insufficient levels have been shown to increase insulin resistance particularly in the brain; this enzyme also breaks down beta-amyloid in the brain (beta-amyloid is the protein that is seen at high levels in the brain as part of the pathology of Alzheimer’s; as IDE breaks down both insulin and beta-amyloid there will be more competition for the enzyme if insulin levels are high).
Vitamin D is a steroid hormone with almost countless roles to play in the body and deficiency is widespread due to fear of sun exposure and a reduction in the consumption of higher fat foods that naturally contain vitamin D. Low levels have been shown to be associated with increased insulin resistance and appropriate supplementation has been shown to increase insulin sensitivity.25,26
Omega-3 fatty Acids
Taking omega-3 fatty acids can reduce triglyceride levels and raise HDL cholesterol levels. Research published in the Journal of Research in Medical Sciences shows that omega-3 fatty acids found in fish are necessary for proper insulin function, preventing insulin intolerance and reducing inflammation.27
- Insulin is a hormone secreted by the beta cells in the pancreas that helps the body to use glucose from carbohydrates in food or to store it for future use. Insulin resistance occurs when insulin receptors on cells in the muscles, fat and liver downregulate and do not respond normally to insulin. This results in a greater demand for insulin from the pancreas and high blood insulin levels.
- Over time the beta cells in the pancreas that are working to make insulin become worn out and can no longer keep pace with the demand for more insulin. Blood sugar increases and pre-diabetes or type 2 diabetes may develop.
- Pre-diabetes – the term is often used to describe blood glucose levels that are higher than normal, but not high enough to be diagnosed with type 2 diabetes; it may also increase the risk of other health conditions.
- Insulin resistance increases the risk for a host of other serious health problems such as cardiovascular disease, stroke and cancer.
- Signs and symptoms of chronically elevated insulin levels are: ‘fatty liver’; hunger and cravings for sugar or carbohydrate rich foods; the development of brownish and dry areas of skin particularly around the neck; fluid retention; poor skin; polycystic ovary syndrome; scalp hair loss to the front and sides (in women).
- There are five steps to help lower insulin resistance – diet, exercise, stress reduction, sleep and the use of herbs and supplements.
- Dietary recommendations include avoiding consumption of sugary foods and reducing portion sizes of other starchy carbohydrates (grains and potatoes). These should only be eaten in small amounts. On the other hand, eat plenty of green vegetables and salads.
- Exercise is an effective way to lower insulin resistance; taking a walk after eating, moving regularly, taking the opportunity to stand-up when possible and high intensity interval training (HIIT).
- Numerous studies show that perceived stress is an independent risk factor for developing type 2 diabetes, so stress management techniques are important
- Chronic sleep deprivation is now recognised as a major contributor to type 2 diabetes. So ensure an eight hour ‘sleep opportunity’ every night. This means if you have to get up at 7am, lights off by 11pm.
- Nutrients that are involved in blood sugar control include chromium, zinc and magnesium, omega-3 fatty acids and vitamin D. There is also research showing cinnamon to support blood sugar control via a number of mechanisms.
If you have questions regarding the topics that have been raised, or any other health matters, please do contact me (Jackie) by phone or email at any time.
firstname.lastname@example.org, 01684 310099
Jackie Tarling and the Cytoplan Editorial Team
- Valabhji J. NHS England » Type 2 diabetes and the importance of prevention. NHS England Blog. https://www.england.nhs.uk/blog/type-2-diabetes-and-the-importance-of-prevention/. Published 2018. Accessed November 1, 2019.
- O’Neil S. Prediabetes: what’s it all about? | Diabetes UK. https://www.diabetes.org.uk/about_us/news/prediabetes-whats-it-all-about. Accessed November 6, 2019.
- Targher G, Day CP, Bonora E. Risk of cardiovascular disease in patients with nonalcoholic fatty liver disease. N Engl J Med. 2010;363(14):1341-1350. doi:10.1056/NEJMra0912063
- Davis GL, Roberts WL. The healthcare burden imposed by liver disease in aging baby boomers. Curr Gastroenterol Rep. 2010;12(1):1-6. doi:10.1007/s11894-009-0087-2
- Ginsberg HN. Insulin resistance and cardiovascular disease. J Clin Invest. 2000;106(4):453-458. doi:10.1172/JCI10762
- Varvel TDD, Stephen T. Metabolic Syndrome-Driving the CVD Epidemic Diabetes: A Growing Threat.
- Orgel E, Mittelman SD. The links between insulin resistance, diabetes, and cancer. Curr Diab Rep. 2013;13(2):213-222. doi:10.1007/s11892-012-0356-6
- Beilby J. Definition of Metabolic Syndrome: Report of the National Heart, Lung, and Blood Institute/American Heart Association Conference on Scientific Issues Related to Definition. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1880831/. Accessed November 8, 2019.
- Albanes D. High Serum Insulin Levels And Risk Of Prostate Cancer — ScienceDaily. https://www.sciencedaily.com/releases/2009/08/090821163511.htm. Accessed November 8, 2019.
- Howard Strickler. High Insulin Levels Raise Risk Of Breast Cancer In Postmenopausal Women — ScienceDaily. https://www.sciencedaily.com/releases/2009/01/090109173207.htm. Accessed November 8, 2019.
- Sun W, Lu J, Wu S, et al. Association of insulin resistance with breast, ovarian, endometrial and cervical cancers in non-diabetic women. Am J Cancer Res. 2016;6(10):2334-2344.
- Harris ML, Oldmeadow C, Hure A, Luu J, Loxton D, Attia J. Stress increases the risk of type 2 diabetes onset in women: A 12-year longitudinal study using causal modelling. PLoS One. 2017;12(2). doi:10.1371/journal.pone.0172126
- Novak M, Björck L, Giang KW, Heden-Ståhl C, Wilhelmsen L, Rosengren A. Perceived stress and incidence of Type 2 diabetes: A 35-year follow-up study of middle-aged Swedish men. Diabet Med. 2013;30(1). doi:10.1111/dme.12037
- Walker M. Why We Sleep: The New Science of Sleep and Dreams – Matthew Walker – Google Books. https://books.google.co.uk/books/about/Why_We_Sleep.html?id=-fKlDgAAQBAJ&printsec=frontcover&source=kp_read_button&redir_esc=y#v=onepage&q&f=false. Accessed November 22, 2019.
- Havel PJ. A scientific review: The role of chromium in insulin resistance. Diabetes Educ. 2004;30(3 SUPPL.):1-14.
- Hua Y, Clark S, Ren J, Sreejayan N. Molecular mechanisms of chromium in alleviating insulin resistance. J Nutr Biochem. 2012;23(4):313-319. doi:10.1016/j.jnutbio.2011.11.001
- Anton SD, Morrison CD, Cefalu WT, et al. Effects of chromium picolinate on food intake and satiety. Diabetes Technol Ther. 2008;10(5):405-412. doi:10.1089/dia.2007.0292
- DOCHERTY, JOHN P., MD; SACK, DAVID A., MD; ROFFMAN, MARK, PhD; FINCH, MANLEY; KOMOROWSKI, JAMES R. M. A Double-Blind, Placebo-Controlled, Exploratory Trial of Chr… : Journal of Psychiatric Practice®. https://journals.lww.com/practicalpsychiatry/Abstract/2005/09000/A_Double_Blind,_Placebo_Controlled,_Exploratory.4.aspx. Accessed November 13, 2019.
- Morris DD. Metabolic Syndrome.
- Richard A. Anderson; Walter F. Schmidt. Cinnamon Extracts Boost Insulin Sensitivity.
- Sircus M. Why 80% of Us Are Deficient In Magnesium. https://www.theepochtimes.com/why-80-of-us-are-deficient-in-magnesium_3121990.html. Published 2019. Accessed November 22, 2019.
- Rodríguez-Morán M, Guerrero-Romero F. Oral magnesium supplementation improves insulin sensitivity and metabolic control in type 2 diabetic subjects: A randomized double-blind controlled trial. Diabetes Care. 2003;26(4):1147-1152. doi:10.2337/diacare.26.4.1147
- Paolisso G, Sgambato S, Pizza G, Passariello N, Varricchio M, D’Onofrio F. Improved insulin response and action by chronic magnesium administration in aged NIDDM subjects. Diabetes Care. 1989;12(4):265-269. doi:10.2337/diacare.12.4.265
- Kim J, Lee S. Effect of zinc supplementation on insulin resistance and metabolic risk factors in obese Korean women. Nutr Res Pract. 2012;6(3):221-225. doi:10.4162/nrp.2012.6.3.221
- Hanafy AS, Elkatawy HA. Beneficial effects of vitamin D on insulin sensitivity, blood pressure, abdominal subcutaneous fat thickness, and weight loss in refractory obesity. Clin Diabetes. 2018;36(3):217-225. doi:10.2337/cd17-0099
- Nazarian S, St. Peter J V., Boston RC, Jones SA, Mariash CN. Vitamin D3 supplementation improves insulin sensitivity in subjects with impaired fasting glucose. Transl Res. 2011;158(5):276-281. doi:10.1016/j.trsl.2011.05.002
- Azadbakht L, Rouhani MH, Surkan PJ. Omega-3 fatty acids, insulin resistance and type 2 diabetes. J Res Med Sci. 2011;16(10):1259-1260.