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High blood sugar (hyperglycaemia)

This blog is the 5th in a series of 5 on the topic of metabolic syndrome risk factors.

To function properly the human body maintains stable levels of glucose in the blood to ensure enough supply to all the body’s tissues and organs without any excess accumulation. These levels are controlled by the regulating hormones, insulin and glucagon. If blood glucose levels are too low, we cannot function well and if blood sugar levels are too high, our body’s tissues and organs are damaged. 

Glucose enters our body in the form of carbohydrates in our food and drink and is stored in our liver and muscles in the form of glycogen. Insulin is produced in the pancreas and released when a spike in blood sugar is sensed. Insulin in the blood then allows glucose - the main energy source used by cells - to be absorbed by our organs and tissues. 

Therefore, glucose regulation occurs in two parts:

  • the first is the release of insulin when the pancreas senses a blood sugar spike;

  • the second in the absorption of blood glucose by tissues which are sensitive to glucose.

High blood glucose levels occur either because the pancreatic cells do not make enough insulin, or the tissue cells around the body become insensitive to the signal of insulin (insulin resistance). 

Insulin resistance is the main cause of type 2 diabetes. Some common causes of muscle, liver and fat not responding properly to insulin include: physical inactivity; obesity, especially visceral obesity; an unhealthy diet, particularly one high in refined carbohydrates and ultra-processed foods; and chronic sleep deprivation. Not enough insulin being produced also happens in conditions as autoimmune disease, chronic pancreatitis and pancreatic cancer.

Disruption to glucose regulation progresses gradually and does not initially cause symptoms. This highlights the importance of both adopting a healthy lifestyle as well as monitoring biomarkers of insulin resistance (for example fasting blood glucose, HbA1c, fasting insulin levels, ALT: AST ratio) in order to detect abnormal glucose control and treat this early. 

Some of the early symptoms of elevated glucose levels include increased thirst and or hunger, frequent urination, blurred vision and headaches. In the longer-term additional symptoms may include fatigue, weight loss and slow-healing cuts and sores. Chronically elevated blood glucose levels are involved in the development of type 2 diabetes as well as many other life-chronic disease including cardiovascular disease, Alzheimer’s disease, cancer and fatty liver disease. 

How can we prevent, improve and even reverse elevated glucose levels caused by insulin resistance? 


  1. Exercise is a powerful tool to manage blood glucose levels. Aerobic exercise is well known to improve insulin sensitivity. Resistance, or strength, training increases muscle mass which provides a greater sink for glucose absorption from your blood.

  2. Your nutrition is of course key - glucose enters our body through the food and beverages we consume. Restricting carbohydrate intake and reducing caloric intake in general are powerful tools in combatting elevated blood glucose levels and metabolic health in general.

  3. Sleep is a third potent modifiable factor. Poor quality sleep and/ or sleep deprivation has a profound effect on both the ability of our pancreas to detect glucose spikes as well as insulin resistance. Even a few days of sleep deprivation will increase you blood sugars to a pre diabetic state.

  4. Stress management also plays a role in managing our blood sugar levels. This is mainly because cortisol, our ‘stress hormone’, is elevated, making us less sensitive to insulin.

In addition to these interventions, there are also medical interventions that can be prescribed by your doctor to improve high blood sugar levels. 

Metformin works by reducing the amount of glucose released by the liver as well as improving insulin resistance. Metformin may have other properties such as reducing cancer risk and may slow ageing and increase life expectancy.

Insulin is used to treat type 1 diabetes but may also be used to help control glucose blood levels in type 2 diabetes by reducing blood sugar levels.

A recently introduced drug used to treat type 2 diabetes is semaglutide (also known by the brand name Ozempic). This drug works by `increasing insulin secretion, suppressing glucagon (a hormone which increase glucose levels in the blood) and slowing gastric emptying. Semaglutide also works to induce weight loss which in turn also aids in increasing metabolic health. It is important to note that use of semaglutide may make your muscles and bones weaker. This associated loss of muscle mass may have a negative effect on lifespan and healthspan if used incorrectly. 

Ideally your fasting blood glucose levels should lie within the range of 4.2 - 4.8mmol/L. Levels beyond the upper threshold may eventually lead to full blown type 2 diabetes as well as many other chronic diseases. As discussed in this series of articles elevated blood glucose often co occurs with one or more of the following: elevated triglycerides, visceral obesity, low HDL and high blood pressure. When three or more of these five criteria are met, a patient has metabolic syndrome.

Metabolic syndrome profoundly increases your risk for cardiovascular disease; death due to cardiovascular disease; stroke; heart attack; many types on cancers, including liver, kidney and gastric; Parkinson’s disease; Alzheimer’s disease and all-cause mortality.

 If you would like to test your personal risk factors for developing chronic diseases of ageing, find out more about the Longevity Annual health check and download the longevity doctor guide to healthy living.


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