Metabolic disorders

Obesity is one of the most common metabolic disorders, affecting about 13 per cent of adults worldwide.²

It occurs when the body consumes more calories than it burns through typical daily activities and exercise. However, the possible causes of obesity are more complex than that. It often results from a combination of causes and contributing factors. These include:

• Lifestyle choices: Smoking, poor diet and lack of regular exercise.
• External factors: Other influences, such as stress, lack of sleep and the diet and behaviour of family and friends, can also play a role.
• Genetics: Genes can affect how body fat is stored, distributed and converted to energy. They can also affect how the body regulates appetite and converts calories during exercise.
• Comorbid conditions: Certain medical conditions, such as thyroid conditions and Cushing’s syndrome, can cause weight gain. Others that cause pain, restricted mobility or reduced energy, such as arthritis, lupus or fibromyalgia, can lead to decreased physical activity levels.
• Medications: Some medications have weight gain as a known possible side effect. These include glucocorticoids (steroids), some antidepressants, anti-seizure medicines, diabetes medicines, antipsychotic medicines and certain beta blockers.
• Other physical factors: These include changes in lifestyle and body functions due to aging or weight gain during pregnancy that can be hard to lose after birth.³

People with obesity are more likely to develop several potentially serious health problems, including:

• Other metabolic disorders
• Cardiovascular disorders
• More severe symptoms of infections and other health issues than otherwise healthy people

Diabetes (or diabetes mellitus) is a condition defined by the level of glucose in the blood. Glucose is a type of sugar formed by the body as it digests the carbohydrates we eat (such as bread, pasta, fruits and vegetables).

Insulin (a hormone created by the pancreas) normally allows the body to convert glucose into energy. It is normal for blood glucose levels to go up and down according to food intake and physical activity levels throughout the day. However, the body needs to constantly regulate insulin production as part of this process.

Diabetes occurs when insulin is either no longer produced, not produced enough or not processed efficiently by the body. The way insulin production is affected and managed depends on the type of diabetes involved. The most common forms of diabetes are type 1, type 2 and gestational diabetes, though there are others.⁴

Diabetes is diagnosed by blood tests that show blood glucose levels have been too high for extended periods. High blood glucose levels (hyperglycaemia or “hypers”) can be indicated by symptoms such as:

• Excessive thirst
• Lethargy
• Frequent urination
• Blurred vision
• Lack of concentration⁵

These are key symptoms that distinguish diabetes from other forms of metabolic disorders. Other symptoms may include slow-healing sores and frequent infections.

Hypers can be triggered by not enough insulin, eating too much carbohydrate food, sickness or infection, stress or reduced physical activity.

Short-term hypers can sometimes be managed by drinking more water or doing enough physical activity to use up the excess glucose in the blood. It may also help to allow time for blood glucose levels to come down on their own (if possible). Prolonged hyperglycaemia can damage blood vessels and nerves. In turn, these can lead to damage in the kidneys, feet, brain and heart.

Symptoms of low blood sugar levels (hypoglycaemia or “hypos”) include:

• Weakness, trembling, shaking or dizziness
• Sweating
• Light-headedness/headache
• Lack of concentration
• Mood changes
• Numbness around the lips/fingers
• Hunger⁵

Hypos can be caused by missing a meal, not eating enough carbohydrates for a given dose of insulin, unplanned physical activity, strenuous exercise, drinking alcohol and some medications. Eating small meals regularly, monitoring blood glucose levels (a range of monitoring devices are available) and avoiding potential triggers can help reduce the risk of hypos.

Hypos can occur suddenly and, if not treated promptly, blood glucose levels can plummet. If caught in time, they can be treated by quickly consuming a fast-acting carbohydrate source such as glucose tablets, jellybeans or a sugary drink. Untreated severe hypos can lead to seizures, coma and death.

Type 1 diabetes

Type 1 diabetes is an autoimmune condition that affects 118,000 people in Australia. It can develop at any age but typically starts in childhood or adolescence. ⁶ Like other autoimmune conditions, it has no known cause, but factors such as genetics and viral infections can play a role.

In type 1 diabetes, the immune system attacks the cells in the pancreas, reducing or stopping their ability to produce insulin. When this happens, glucose in the blood can’t get into muscle cells so they can’t use it as an energy source. Instead, they break down fat for energy, which produces ketones (acidic chemicals).

High levels of ketones are toxic and can lead to diabetic ketoacidosis. This is an urgent, life-threatening medical condition. Ketoacidosis symptoms include:

• Abdominal pain
• Nausea and vomiting
• Deep, fast breathing
• Fruity-smelling breath
• Drowsiness

People with type 1 diabetes need to inject insulin each day. This can be done by self-injection or using a small auto-injecting pump worn on the body. The dosage amount and frequency depend on the blood glucose level at the time. Therefore, people with this condition must constantly monitor their carbohydrate intake, physical activity and blood sugar levels.

Type 2 diabetes

Type 2 diabetes affects around 1.3 million Australians. ⁷ It usually develops in adults over 45 years but is now seen in younger people as well.

Many well-known risk factors can contribute to the development of type 2 diabetes but there is no single cause for everyone. The most common risk factors for developing type 2 diabetes include:

• Age and ethnicity: Including people aged over 55 or younger adults who are of Australian Aboriginal or Torres Strait Islander, Pacific Islander, Maori, Asian, Middle Eastern, North African or Southern European descent.
• Genetics: Such as people with a close relative with type 2 diabetes.
• Other conditions: Such as obesity, high blood pressure, cardiovascular disease, polycystic ovarian syndrome and gestational diabetes.
• Some medications: Such as antipsychotics, glucocorticoids (steroids), beta blockers, statins and diuretics. ⁸
• Lifestyle factors: Such as low levels of physical activity, unhealthy eating habits and smoking.

Unlike type 1 diabetes, up to 60 per cent of type 2 diabetes can be prevented through lifestyle changes such as ceasing smoking, improving diet and exercising regularly.⁹

If the body is exposed to too much blood sugar over an extended period, it can lead to insulin resistance. This means the pancreas produces more insulin to get more blood sugar converted to energy.

Over time, the body stops responding well to insulin (it becomes resistant to it). The blood sugar remains high so the cycle repeats until the pancreas can’t keep up. If insulin resistance is not effectively managed, it can lead to prediabetes and type 2 diabetes.

People with type 2 diabetes may have no noticeable symptoms for a long time (sometimes years) so regular screening for those at risk is important.

In the early stages, type 2 diabetes can often be well-managed through lifestyle changes alone. Those whose condition progresses may need to add oral medications or, eventually, insulin injections to keep their diabetes under control.

Gestational diabetes

Gestational diabetes occurs in some women during pregnancy. It causes the mother’s blood sugar levels to be higher than normal so it can increase the risk of pregnancy complications. In most cases, it goes away after the baby is born.

Gestational diabetes will not lead to the baby being born with diabetes; however, it can increase the risk of the mother and/or baby developing type 2 diabetes later in life. ¹⁰

Women at increased risk of developing gestational diabetes include those who:

• Have had gestational diabetes in a previous pregnancy
• Are aged 40 years or over
• Have other risk factors similar to those for type 2 diabetes

Gestational diabetes can often be well managed through lifestyle changes, along with regular monitoring by appropriate healthcare professionals. In some cases, the mother may need oral medications or insulin injections during the pregnancy.

Metabolic syndrome refers to a cluster of related conditions that occur together, leading to an increased risk of cardiovascular conditions and type 2 diabetes. These are:

• Raised blood pressure (hypertension)
• Elevated triglyceride levels (too much of a type of fat called triglycerides in the blood)
• Lowered high-density lipoprotein cholesterol (known as the “good” cholesterol)
• Insulin resistance
• Abdominal obesity

The presence of any three of the five risk factors indicates metabolic syndrome. More than 35 per cent of Australian adults have metabolic syndrome. This is higher in people with diabetes. ¹¹

As these conditions are all interlinked, it is hard to know which (if any) is the main cause of metabolic syndrome in each person.

The symptoms and management of metabolic syndrome vary depending on the combination of conditions involved. Many people may not have any symptoms so healthcare providers and those with related conditions need to be aware of the risks and monitor the contributing conditions closely.

Other conditions that may develop as a result of metabolic syndrome include:

• Polycystic ovarian syndrome (PCOS)
• Fatty liver
• Cholesterol gallstones
• Asthma
• Sleep problems
• Some forms of cancer¹²

¹ Medical News Today: What to know about metabolic disorders. https://www.medicalnewstoday.com/articles/metabolic-disorders

² Yang M, Liu S, Zhang C. The Related Metabolic Diseases and Treatments of Obesity. Healthcare (Basel) (2022) Aug 25;10(9):1616. doi: 10.3390/healthcare10091616. PMID: 36141228; PMCID: PMC9498506. https://pmc.ncbi.nlm.nih.gov/articles/PMC9498506

³ Mayo Clinic: Obesity Overview. https://www.mayoclinic.org/diseases-conditions/obesity/symptoms-causes/syc-20375742

⁴ Diabetes Victoria: Other Diabetes Types. https://www.diabetesvic.org.au/about-diabetes/other-diabetes-types

⁵ Diabetes Australia: Hypoglycaemia (hypo) and Hyperglycaemia. https://www.diabetesaustralia.com.au/managing-diabetes/hypo-hyperglycaemia

⁶ Diabetes Australia: Type 1 Diabetes, https://www.diabetesvic.org.au/about-diabetes/type-1-diabetes

⁷ Diabetes Australia: Diabetes in Australia. https://www.diabetesaustralia.com.au/about-diabetes/diabetes-in-australia

⁸ Diabetes Australia: What to Know About Medically Induced Diabetes. https://www.diabetesaustralia.com.au/blog/medically-induced-diabetes

⁹ Diabetes Victoria: Type 2 Diabetes. https://www.diabetesvic.org.au/about-diabetes/type-2-diabetes

¹⁰ Diabetes Australia: Gestational Diabetes. https://www.diabetesaustralia.com.au/about-diabetes/gestational-diabetes

¹¹ Better Health Channel: Metabolic Syndrome. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/metabolic-syndrome

¹² Johns Hopkins Medicine: Metabolic Syndrome. https://www.hopkinsmedicine.org/health/conditions-and-diseases/metabolic-syndrome