Type 2 diabetes mellitus

Diabetes is a lifelong chronic condition, affecting approximately 225,840 people in Ireland.¹ It is defined as a group of metabolic disorders which are either caused by inadequate insulin production (type 1), or insulin resistance (type 2) or a combination of both of these factors. The defining characteristic of the insulin deficiency or resistance is a raised blood glucose level which can have serious detrimental effects on the person’s health. 

The term diabetes mellitus comes from the Latin ‘diabetes’, meaning to pass through, and ‘mellitus’ meaning honeyed or sweet.

Type 2 diabetes

Type 2 diabetes, previously known as ‘non-insulin dependent’ or ‘adult-onset’ diabetes due to its occurrence mainly in people over the age of 40, has been diagnosed with increased frequency since 2004.³

It is the most common form of diabetes mellitus, accounting for nearly 90% of all adult cases² and has a rising prevalence in children.³ It is estimated that by 2030, almost 280,000 people will have type 2 diabetes. This will mean that 7.5% of the population of Ireland will have the condition.¹

Type 2 diabetes is caused by a combination of insulin resistance and relative insulin deficiency. This results in poor glucose absorption, leading to persistent increased blood glucose levels (hyperglycaemia). Common risk factors associated with developing type 2 diabetes include obesity, lack of physical activity, a family history of diabetes and having high blood pressure or high levels of cholesterol. 

If not successfully managed, it can lead to long-term complications such as reduced quality of life, reduced life expectancy, psychological problems, and microvascular and macrovascular complications.² Type 2 diabetes can be managed using a stepwise approach with a combination of diet and lifestyle changes, oral antidiabetic drugs and insulin.

In comparison, type 1 diabetes is classified as an absolute insulin deficiency, where the body does not produce enough insulin due to the insulin producing cells within the pancreas being destroyed. As a result of this, if the person were not to use insulin replacement therapy, they would die within days or weeks. 

Risk factors for type 2 diabetes

Risk factors for type 2 diabetes can be a combination of genetic and environmental factors. Environmental factors are largely influenced by lifestyle such as obesity and inactivity, these account for 80-85% of the overall risk of developing type 2 diabetes. Overeating and inactive lifestyles can exacerbate insulin resistance and poor dietary habits, such as low fibre and food with a high glycaemic index (cakes, pastries etc.) may increase the risk of obesity, which in turn increases the risk of type 2 diabetes. 

Genetic factors, such as ethnicity and a family history of type 2 or gestational diabetes also increases the person’s risk. People with a family history of type 2 diabetes are two to six times more likely to develop the condition than people without, and if a child is born to a mother with gestational diabetes they have a six-fold increased risk of developing the condition. 

People of Asian or African descent are two to four times more likely to develop the condition than Caucasians. Other risk factors include certain drug treatments such as statins or corticosteroids, and other pre-existing conditions such as polycystic ovarian syndrome and metabolic syndrome. 

Diagnosing type 2 diabetes

Early diagnosis is seen as the best starting point for living well with diabetes; early detection speeds the treatment of cardiovascular risk factors, particularly improving the management of lipids and blood pressure.⁴ Diabetes is diagnosed mainly on clinical grounds; it should be suspected in the presence of key diagnostic factors including: the presence of common risk factors such as family history and obesity, and persistent hyperglycaemia. Other characteristic symptoms such as fatigue, blurred vision, thirst and weight loss are usually not severe or may be absent. Diabetes is usually diagnosed by a blood level of HbA1c of 48mmol/mol (6.5%) or more,⁵ however the diagnosis should never be based on a single abnormal HbA1c or fasting blood glucose level; at least one additional abnormal result is required for a firm diagnosis. 

Due to the increased prevalence of type 2 diabetes in children, it is important to suspect diabetes in a child if they present with the following symptoms: persistent hyperglycaemia, strong family history of type 2 diabetes, obesity, or are of African or Asian family origin. Children with type 2 diabetes typically have no additional features of type 1 diabetes. These features of type 1 diabetes are rapid onset of symptoms, weight loss or signs or symptoms suggesting the diabetic emergency of ketoacidosis. The signs of ketoacidosis include fast, deep breathing, abdominal pain, nausea, vomiting, weakness and lethargy and dehydration. 

When thinking about the possibility of diabetes in a child, type 1 should always be suspected as being the likeliest diagnosis.³ If diabetes is suspected, the child should be immediately referred to a multidisciplinary paediatric diabetes care team for confirmation of diagnosis. 

Complications

There are several complications which can arise from type 2 diabetes; this risk can be greatly reduced by active management of blood glucose levels and following a self-management programme. Adults with type 2 diabetes are 40 times more likely to die of macrovascular than microvascular complications of diabetes.⁵

Macrovascular complications include cardiovascular disease, cerebrovascular disease and peripheral arterial disease. Adults with type 2 diabetes are twice as likely to die of a stroke compared to those without,⁵ and cardiovascular disease accounts for 52% of deaths in people with type 2 diabetes. Some 20% of all hospital admissions for heart failure, myocardial infarction and stroke are in people with diabetes.

Microvascular complications include nephropathy, retinopathy and neuropathy. About three in four people with diabetes will develop chronic kidney disease in their lifetime, with kidney disease accounting for around 11% of deaths in type 2 diabetes. 

Chronic renal disease is driven by uncontrolled blood pressure and glucose, and increases the risk of CVD by four-to-tenfold.⁵ Diabetes is one of the leading causes of preventable blindness in Ireland, responsible for 4% of people who are registered blind. People with diabetes are also 30 times more likely to have an amputation compared with the general population due to chronic painful neuropathy.

Metabolic complications such as diabetic ketoacidosis can arise from poor blood glucose management, along with dyslipidaemia which is a risk factor for CVD. Other complications include psychological issues such as anxiety and depression; reduced quality of life from constant management of blood glucose; reduced life expectancy; and being more susceptible to urinary tract and skin infections, among others.

Assessment

People with diagnosed type 2 diabetes should undergo regular examinations and assessments, usually every four to six months, however some may benefit from monthly visits,⁵ for early detection of complications. At every review appointment, the following should be carried out: 

•
The person’s body mass index (BMI) should be calculated to make sure patient is managing their weight appropriately

•
A psychological assessment to check for depression or anxiety

•
Record smoking status 

•
The person should be examined for neuropathy and any associated complications 

•
Every three to six months, the patient should have HbA1c levels measured to check for hyperglycaemia, and once a year they should be screened for retinopathy, diabetic foot problems, nephropathy and cardiovascular risk factors. 

Treatment 

A care plan for type 2 diabetes should be tailored to the individual and their specific circumstances. This plan should take into account their personal preferences, risks from polypharmacy and ability to benefit from interventions.²

Lifestyle advice and drug treatments should be offered to the person to meet treatment targets for HbA1c levels to minimise long-term vascular problems. The recommended HbA1c target for people who are managed by lifestyle and diet with or without drugs not associated with hypoglycaemia is 48mmol/mol (6.5%). For children, the recommended target is 48mmol/mol (6.5%) or lower; the child and carer should be made aware that this is the ideal level to minimise the risk of long-term complications.³

Metformin is the recommended initial anti-diabetes treatment for adults with type 2 diabetes, unless this is contraindicated, eg. if the person has endstage renal disease. Anti-diabetes treatment for children should be started by the multidisciplinary paediatric diabetes care team, which in type 2 diabetes is usually standard-release metformin.³

Lifestyle advice

The effectiveness of diabetes management ultimately depends on the person’s compliance with recommended treatment. Patient education therefore plays a key role in the treatment plan for the person. It is important to stress the need to understand core principles in diabetes management. These principles include a healthy balanced diet, adequate physical activity, smoking cessation, adherence to prescribed medication, foot hygiene and the need for regular assessment.⁵

A structured education programme should be recommended to the person or carer after a diagnosis of type 2 diabetes.²  Group education programmes are also recommended as the preferred option for this approach to structured education for patients, provided that they meet the cultural, linguistic, cognitive and literacy needs of the person and contain all the appropriate educational components.²

Dietary advice should be provided, ideally by a dietitian,⁵ centred on the principles of healthy eating with a focus on foods that do not adversely affect blood glucose levels.⁶

Emphasis should be placed on the importance of a balanced diet including plenty of fibre, low glycaemic index foods, low-fat dairy products and oily fish, while controlling the intake of foods high in saturated fats and transfatty acids; saturated fat should be limited to < 7% of calories.⁵

It is recommended that people with type 2 diabetes take a blood glucose test before and two hours after meals. This will enable them to see which foods, and what quantities, are appropriate for them.⁶ If the person is overweight, a body weight loss target of 5-10% is recommended.

Increased physical activity should be encouraged as regular exercise may lower blood glucose levels due to muscles using glucose for energy. All adults aged over 19 years of age should aim to be active daily, with three to four sessions of aerobic physical activity per week.⁵

In addition to general health benefits, regular exercise appears to have a beneficial effect on insulin action, can reduce the increased risk of cardiovascular issues in the medium and long-term, and help with weight management.⁴

Other lifestyle choices should be discussed, including the impact on the person’s health from smoking and alcohol intake. 

For children, additional guidance should be offered on annual immunisations and diabetes identification. Annual immunisation against influenza is recommended for all children and young people with diabetes, and pneumococcal vaccination is also recommended for those who need insulin or oral hypoglycaemic drugs.³ Diabetes identification should also be worn in the case of emergency, for example a Medic- Alert bracelet, necklace or watch (www.medicalert.org.uk) or a diabetes ID card (www.diabetes.co.uk).

Support groups are available to people with type 2 diabetes, with information on how to contact them and benefits of memberships (see www.diabetes.ie)

References

1. Diabetes Ireland. Available at: https://www.diabetes.ie/about-us/diabetes-in-ireland/
2. National Institute for Health and Care Excellence. Type 2 diabetes in adults: management NICE Guidelines [NG28]. Published December 2015, Available from: https://www.nice.org.uk/guidance/ng28/chapter/Introduction [Accessed June 28,2016] 
3. National Institute for Health and Care Excellence. Diabetes (type 1 and type 2) in children and young people: diagnosis and management NICE Guidelines [NG18]. Published August 2015, Available from: https://www.nice.org.uk/guidance/ng18/chapter/Introduction [Accessed June 28,2016] 
4. World Health Organisation. Global report on diabetes. Published April 2016, Available from [http://apps.who.int/iris/bitstream/10665/204871/1/9789241565257_eng.pdf?ua=1&ua=1]
5. BMJ Best Practice. Type 2 diabetes in adults. Published November 2015, Available from [http://bestpractice.bmj.com/best-practice/monograph/24.html]
6. Diabetes.co.uk Diet for Type 2 Diabetes. [http://www.diabetes.co.uk/diet-for-type2-diabetes.html]