Janelle McAlpine MMRes BA (Human Bioscience) BMid
Registered Midwife
When a food containing carbohydrate is eaten, your body breaks down the carbohydrate into sugar (called glucose). This can then be used as energy by the cells in your body. Diabetes is a condition where your body can’t properly control the amount of glucose in your blood. Normal blood glucose levels range between 3.0 and 7.8 mmol/L.
Blood glucose levels in the body are controlled by the actions of two hormones – INSULIN and GLUCAGON.
Insulin and glucagon are produced by two types of cells in the pancreas. Beta cells produce and release insulin, and alpha cells produce and release glucagon.
Insulin is needed for transferring glucose from the bloodstream to enter the body cells and be converted to energy. It acts like a key to the cells glucose lockout system. In people with diabetes, blood glucose levels are often higher than normal because either the body does not produce insulin (type 1 diabetes) or cannot use insulin properly (type 2 diabetes and gestational diabetes).
The pancreas is constantly alternately releasing the two hormones in response to the blood sugar levels detected by these cells. When blood glucose is high, beta cells release insulin. When blood glucose levels are low, the alpha cells release glucagon. Glucagon is the messenger that tells the body to start releasing its glucose stores. There is always some overlap and over correction happening. It acts much like a seesaw.
Here’s one way of understanding how the blood glucose control system works….
Glucose is the currency of energy (like money).
Let’s assume that a person is smart with their money, the way a body is smart with its glucose.
Payday comes (money in)…
- You spend what you need to now.
- You put some away for later in the week.
- You put the rest in a savings account just in case down the line you have a lean week.
Your body uses glucose the same way….
- You make the energy you need now
- You put some fuel away in short term storage
- You put some in long term storage
And when you run out of money….
- You stop spending
- You use your short term reserves
- You scrounge around and see what money you can make out of what you have got lying around.
- If that runs out you access your long term savings.
When readily available glucose runs out…
- The cells slow down energy production
- You use the glycogen stores
- You make energy from bits and pieces
- You access your long term storage
High levels of glucose in the bloodstream can lead to short term complications such as:
- frequent urination
- being extremely thirsty and drinking lots of fluids
- being constantly tired
- having blurred vision
- having frequent skin infections and being slow to heal
People with diabetes should aim for blood glucose levels between about 4.0 and 8.0 mmol/L, but individual targets should always be discussed with your diabetes health care professional.
Controlling diabetes is important to prevent serious long term complications such as:
- heart and circulation problems
- infections
- kidney disease
- eye problems, which can lead to blindness
- nerve damage to the lower limbs and other parts of the body
According to the Australian Health Survey, 1.0 million people had Diabetes Mellitus in 2011-12 (4.6%) (1)
Types of diabetes
There are three main types of diabetes:
Type 1 diabetes
Type 1 diabetes affects less than 1% of all Australians. It can appear at any age, but most commonly in childhood and early adult life. People with type 1 diabetes cannot produce enough insulin, and therefore they must inject themselves with insulin several times a day for the rest of their life.
Type 2 diabetes
Type 2 diabetes is the most common form of diabetes, affecting 7.1 % of all Australians over the age of 25 . This type of diabetes most often occurs in people over 40 who are overweight and/or have a family history of type 2 diabetes, however it is now being diagnosed in children. In type 2 diabetes, the body is unable to use insulin properly or the pancreas may not make enough insulin. Type 2 diabetes may be treated by diet, exercise and/or tablets. Insulin injections may be required.
Gestational diabetes
Gestational diabetes occurs in around 5% of all pregnant women in Australia, and usually starts between 24 and 28 weeks of pregnancy. The pregnancy hormones combined with a predisposition for poor insulin control, results in increased blood glucose levels in the mother and the baby. For most women with gestational diabetes, the diabetes will disappear after the baby is born. However, women who have gestational diabetes have a higher likelihood of going on to develop type 2 diabetes later in life than those who don’t.
Managing diabetes
For people who need to use insulin, regular exercise and a healthy diet that works with their insulin regime is the key to controlling blood glucose levels. They also need to consider the timing, amount and type of carbohydrate foods they eat, as well as the timing, amount and type of insulin they take. Regular blood glucose testing is necessary to manage insulin-dependent diabetes regardless of which type they have..
Healthy eating tips for people with diabetes
A healthy diet used in the treatment of diabetes is similar to the diet recommended for all Australians. To help manage your condition, Diabetes Australia recommends:
1. Eating regular meals and healthy snacks throughout the day
2. Meals be based on high fibre carbohydrates such as wholegrain breads and cereals, beans, lentils, vegetables and fruits
3. That the amount of fat (particularly saturated fat) is limited by choosing lean meats and low fat dairy foods, avoiding fried takeaway foods, pastries and biscuits whenever possible
4. That weight is kept within the healthy weight range by matching the amount of energy taken in with the energy put out.
Carbohydrates and the glycaemic index
The amount of carbohydrate consumed is the most important factor that influences blood glucose levels after a meal. Carbohydrate rich foods include breads, cereals, rice, pasta and grains, fruit (and juice), legumes and some vegetables such as potato, sweet potato and corn. Milk and yogurt are also a source of carbohydrate due to the milk sugar lactose.
The glycaemic index (GI) is a tool that helps people to choose foods that help them control blood glucose levels. The GI ranks foods containing carbohydrates from 0-100 based on whether they raise blood sugar levels a lot, moderately or a little. Carbohydrate containing foods that are digested quickly will result in a high blood glucose levels and therefore have a high glycaemic index (these are called high GI foods). Foods with a GI 70 and above are classified as high GI.
Foods that are digested more slowly raise blood glucose levels at the same rate, and so have a lower glycaemic index (low GI foods). Foods with a GI 55 and below are low GI foods. Eating foods with a low GI can help people control their blood glucose levels. The GI is also used by people who want to control their energy availability and appetite. Eating moderate amounts of low GI carbohydrate foods regularly over the day will help you maintain consistent blood glucose levels.
Low GI food choices include:
Milk and dairy foods – reduced or low fat varieties of milk and dairy foods.
Bread – wholegrain, fruit loaf and sourdough.
Breakfast cereals – traditional porridge, natural muesli and some high fibre varieties.
Pasta and noodles – all varieties.
Some varieties of rice – eg ‘Basmati’
Grains – barley, bulgur and semolina.
Legumes – beans (e.g. baked beans, kidney beans, soy beans), peas and lentils.
Fruit – apple, orange, pear, peach, grapes, kiwi fruit, banana, plums.
Vegetables – most vegetables have low amounts of carbohydrate and therefore have little effect on your blood glucose levels. Vegetables with a significant amount of carbohydrate include potato, sweet potato, yams and sweet corn. Orange sweet potato, yams and sweet corn are the lower GI choices.
Information courtesy of Diabetes Australia
Reference:
- Australian Bureau of Statistics. Australian Health Survey: Updated Results, 2011-2012. Canberra: 2013.