By: An extract from Understanding Type 2 Diabetes by Professor Merlin Thomas
The following is an extract from the book Understanding Type 2 Diabetes. The book is available from Exisle Publishing and wherever good books are sold.(RRP $19.99) The human body runs on fuel, like the petrol in your car. Glucose is chiefly used to fuel chemical reactions inside the body.
To keep the brain and body healthy, blood glucose levels are normally kept within a narrow range, balanced by the actions of insulin and other hormones.
Insulin is made and released by the beta-cells of the pancreas to coordinate the body's response to rising glucose levels.
Diabetes occurs when there is not enough insulin (or its functions) to keep glucose levels under control.
High glucose levels usually start out as a silent problem. Most people diagnosed with type 2 diabetes are completely unaware they have it, and have probably had it for many years.
The name glucose comes from the Greek word glukus, meaning 'sweet'. Glucose is a sweet sugar. It is also the major sugar that circulates inside your blood, so the terms 'glucose' and 'sugar' are often used interchangeably when managing diabetes. But glucose is not the same thing as the white sugar used in cooking or in your coffee.
The human body runs on fuel, like the petrol in your car. Glucose is chiefly used to fuel chemical reactions inside your body. This is known as metabolism. Metabolism provides the vital energy for every cell to do what needs to be done. Every cell needs fuel for its metabolism. Most cells will eat anything that is available. But your brain is a very picky eater - it will only eat glucose.
However, the problem is that your brain has little stored glucose of its own. It can't make glucose itself and won't use any other fuel if glucose runs out. Instead, it must rely on the glucose dissolved in your blood being present all of the time to maintain continuous supply and continuous functioning. From the brain's point of view, blood sugar is as important as the oxygen in the air you breathe: it can only function for a few minutes without either before it stops working altogether.
To guarantee your brain keeps running night and day, the body must ensure that glucose is always present in your blood in roughly the same concentration. To achieve this level of control is not easy. Some days you might eat a few pieces of cake, a sandwich or even a huge bowl of pasta. Other times you might eat hardly anything at all. Yet through it all, glucose levels will normally fluctuate only very slightly:
between 4-6 mmol/L (72-108 mg/dL) when you are not eating and
between 4-7 mmol/L (72-126 mg/dL) after a meal.
This amazing level of control is achieved thanks to an elaborate system of checks and balances that carefully regulates how much glucose is going into the blood and how much is going out.
In essence, diabetes is the state in which this balance fails and glucose levels rise.
Every time you eat or drink something that contains any carbohydrate (also known as carbs) your body gets a dose of sugar. Whether you are eating chocolate cake or spaghetti or drinking a Coke, the carbs contained in each product are broken down by your digestion into simple sugars, one of which is glucose.
As these sugars are digested and absorbed, they trigger the release of hormones, the most important of which is insulin. Hormones are chemical signals that communicate a message from one part of the body to another, usually via the bloodstream. Insulin is made and released by the beta-cells of the pancreas.
The message insulin sends coordinates the body's response to rising blood glucose levels. This message tells the cells of the liver, muscles and fat to take away glucose from the blood (and store it for later use). It also tells the liver to stop making and releasing any extra glucose, which is rendered unnecessary by having just had a sugary meal.
This is a proportional response. The greater the amount of sugar contained in a product and the faster it hits your system, the greater the amount of insulin that is released. This keeps glucose levels from rising too fast or too high. In contrast, a meal that is low in sugar or contains sugars that are only slowly digested will need to trigger a proportionally smaller insulin response to make sure glucose levels don't drop too rapidly.
The net result of this finely balanced system is that, in people without diabetes, glucose levels in the blood only rise slightly and very briefly following a meal, regardless of what they eat.
When you are not eating, such as at night, your brain still needs glucose to keep functioning. So to keep up with the brain's unceasing demands, the liver slowly releases its glucose stores and also manufactures new glucose, which it releases into the blood like a kind of controlled drip feed for your hungry brain.
To make this happen before glucose levels in the blood start to fall, the pancreas immediately stops releasing insulin and starts making other hormones such as glucagon. These hormones send a different message. They say that any unnecessary uptake of glucose must now stop, leaving any glucose for your fussy brain. Also, the brakes that insulin has placed on the liver's glucose production should be removed, to start the drip feed.
Again, the rate at which glucose is released into the blood is finely balanced to match the rate at which the body (and in particular the brain) uses glucose. So glucose levels in the blood don't fall very much, if at all, between meals in people who do not have diabetes. Even if you skip a meal, or wish to fast for several days, glucose levels always remain sufficient for the brain to keep working.
So in people without diabetes, day and night, feeding or fasting, the levels of glucose in their blood do not rise or fall much at all, balanced by the actions of insulin and other hormones.
Diabetes only occurs when there is not enough insulin to keep this balance and maintain glucose levels under tight control.
And why this happens is complicated. Many different factors can contribute to the decline and loss of insulin's functions, leading ultimately to the development of type 2 diabetes.
Type 2 Diabetes - 3 strikes and you're out
Type 2 diabetes will affect at least one in every three people at some point during their lifetime. But it will not affect everyone.
There are many people who are overweight who don't get diabetes. There are many who have a poor diet or the wrong genes, and they don't get diabetes either. To get type 2 diabetes you need all three things to happen.
You need the beta-cells of the pancreas to be overworked.
You need too much fat in the wrong places.
You need to be susceptible (such that your ability to compensate for overwork of your beta-cells and too much fat in your body ultimately fails).
Type 2 diabetes is made more likely if any one of these factors is increased. For example, an unhealthy diet will increase the work of the pancreas and increase the risk of diabetes. Similarly, being overweight can increase your risk of diabetes even without a strong family history. Equally, some people have a strong family history of diabetes so it doesn't take much extra work or being very overweight for diabetes to occur. Of course, if more than one of these factors is increased, your risk will multiply and diabetes will become both more likely and more likely to occur at an earlier age.
At the same time, the best ways to prevent and treat diabetes will target these important areas. For example, changes in the amount and types of sugar and fibre in your diet can reduce the strain on your pancreas to produce large amounts of insulin. Getting rid of any extra fat in your body through diet and increased physical activity will reduce its limiting effects on your metabolism and reduce insulin resistance.
In its early stages, diabetes is reversible. For example, gastric bypass surgery dramatically reduces food intake and causes a great decline in the amount of ectopic fat in your body. This is able to 'cure' type 2 diabetes such that many people having this procedure can keep control of their glucose levels without the need for any medications. It requires complicated, invasive major surgery that is not an answer for the over 430 million people worldwide with type 2 diabetes. But it does illustrate that once you understand some of the factors involved in the development of diabetes (like ectopic fat), and target them early enough, anything is possible.