Type 2 Diabetes: Diagnosis

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Type 2 Diabetes: Diagnosis

What is diabetes?

Diabetes mellitus is a group of metabolic disorders where hyperglycaemia (random plasma glucose more than 11 mmol/L) is caused by deficient insulin secretion, resistance to the action of insulin, or both.

Diabetes mellitus is classified as:

• Type 1 diabetes — an absolute insulin deficiency which causes persistent hyperglycaemia.
• Type 2 diabetes — insulin resistance and a relative insulin deficiency which results in persistent hyperglycaemia.
• Gestational diabetes — hyperglycaemia develops during pregnancy and usually resolves after delivery, although the woman is at increased risk for overt type 2 diabetes in the future.

Other specific types of diabetes include:

• Monogenic diabetes (due to a single gene defect; previously known as 'maturity-onset diabetes in the young').
• Diabetes secondary to pathological conditions or diseases (such as pancreatitis), trauma, or pancreatic surgery.
• Drug- or chemically-induced diabetes (such as from long-term corticosteroid treatment).

What causes type 2 diabetes?

Beta cells in the pancreas produce insulin.

When muscle cells, fat and liver cells are insensitive to insulin this leads to an increased demand of the production of insulin by beta cells.

Type 2 diabetes is caused by a combination of insulin resistance (where the body is unable to respond to normal levels of insulin) and insulin deficiency (where the pancreas is unable to secrete enough insulin to compensate for this resistance).

Insulin resistance is exacerbated by overeating, inactivity, and other risk factors.

What are the risk factors for type 2 diabetes?

• Obesity and inactivity — people who are overweight or obese (especially central obesity) and/or have inactive lifestyles are at increased risk of developing type 2 diabetes, as overeating and inactivity can exacerbate insulin resistance. Obesity accounts for 80–85% of the overall risk of developing type 2 diabetes.
• Family history — type 2 diabetes tends to cluster in families. People with a family history of diabetes are 2–6 times more likely to have diabetes than people without a family history. The risk of developing type 2 diabetes is about 15% if one parent has type 2 diabetes and 75% if both parents have type 2 diabetes.
• Ethnicity — people of Asian, African, and Black communities are 2–4 times more likely to develop type 2 diabetes than white people.
• Metabolic syndrome — insulin resistance is commonly associated with the metabolic syndrome, defined as a combination of raised blood pressure, a disturbance of blood lipid levels, fatty liver, abdominal adiposity (increased waist circumference), and a tendency to develop thrombosis.
• History of gestational diabetes — this confers a sevenfold increased risk of developing type 2 diabetes later in life. Children born to mothers with gestational diabetes have a six-fold increased risk of developing type 2 diabetes.
• Poor dietary habits — low fibre, high glycaemic index (GI) diet may increase the risk of being overweight or obese, which in turn increases the risk of developing type 2 diabetes.
• Drug treatments — certain drug treatments, for example statins, corticosteroids, and combined treatment with a thiazide diuretic plus a beta-blocker, can increase the risk of developing hyperglycaemia and type 2 diabetes.
• Polycystic ovarian syndrome — this increases the risk of impaired glucose regulation and hence type 2 diabetes.
• Low birth weight for gestational age — there is some evidence that preterm birth before 35 weeks of gestation is associated with an increased risk of type 2 diabetes developing in adult life.

How common is diabetes type2?

Diabetes is one of the most common chronic diseases in the UK, and its prevalence is increasing

There are approximately 3.5 million people with diagnosed diabetes, including 31,500 children and young people under the age of 19 years.

There are approximately 550,000 people with undiagnosed diabetes.

Type 2 diabetes can occur in all age groups and is increasingly being diagnosed in children (due to the rise in obesity)

• About 90% of adults currently diagnosed have type 2 diabetes.
• About 1.9% of children and young people currently diagnosed have type 2 diabetes.

What is the prognosis for a patient with type 2 diabetes?

With optimal management, people with type 2 diabetes can participate normally in the usual activities of daily life. However,

• Insulin deficiency in type 2 diabetes usually progresses with time and commonly worsens over a period of years.
• Initially, lifestyle interventions including improved diet and increased physical activity are used to manage type 2 diabetes. However, over time, many people will require antidiabetic drug treatments (including insulin).
• Complications of type 2 diabetes can result in reduced quality and quantity of life. Diabetes accounts for about 15–16% of deaths in England, with life expectancy for people with type 2 diabetes reduced by an average of up to 10 years. In people with type 2 diabetes, the risk of death is 32% greater than expected and is mostly in younger people and females.

What are the complications of type 2 diabetes?

Macrovascular complications — cardiovascular disease (CVD, for example myocardial infarction), cerebrovascular disease (for example stroke and transient ischaemic attack), and peripheral arterial disease.

• CVD is a major cause of death and disability in people with diabetes.
• People with type 2 diabetes have a twofold increased risk of stroke within the first five years of diagnosis compared with the general population.
• About 20% of hospital admissions for heart failure, myocardial infarction, and stroke are in people with diabetes (type 1 or 2).

Microvascular complications — nephropathy, retinopathy, and neuropathy.

• Nephropathy — kidney damage is the largest cause of renal failure in people of working age in the UK. About 3 in 4 people with diabetes will develop some stage of chronic kidney disease during their lifetime. Kidney disease accounts for 11% of deaths in people with type 2 diabetes.
• Retinopathy — diabetes is the leading cause of preventable blindness in people of working age in the UK, and diabetic retinopathy accounts for 7% of people who are registered blind in England and Wales.
• Chronic painful neuropathy — this is estimated to affect up to 26% of people with diabetes, and people with diabetes are estimated to be up to 30 times more likely to have an amputation compared with the general population.
• Autonomic neuropathy — this presents in different ways and affects a variety of organs, including the skin (sweating), blood vessels (postural hypotension), gastrointestinal tract (gastroparesis and diarrhoea), heart, bladder function, and sexual function (35–90% of men with diabetes have erectile dysfunction). It may also blunt the symptoms of hypoglycaemia.

In addition it can also cause the following non-vascular complications…

• Metabolic complications — dyslipidaemia and diabetic ketoacidosis (DKA).
• Psychological complications — these include anxiety and depression. In addition, in children and young people, behavioural and conduct disorders, family/relationship difficulties, and risk-taking behaviour (including non-adherence to recommended treatment).
• Reduced quality of life — people with diabetes face significant challenges to daily living, for example managing episodes of hypoglycaemia and hyperglycaemia, self-monitoring of blood glucose, and the need to plan normal daily activities (such as eating and exercising).
• Infections — people with diabetes are prone to infections, particularly of the urinary tract and skin.
• Reduced life expectancy
• Dementia — people with type 2 diabetes have a 1.5–2.5-fold increased risk of dementia; the exact reason for this is currently unknown.

How do I diagnose type 2 diabetes in adults?

Suspect type 2 diabetes in an adult who presents with:

• Persistent hyperglycaemia, which means HbA1c more than 48 mmol/mol [6.5%] or random plasma glucose more than 11 mmol/L.

Note that the characteristic features; thirst, polyuria, blurred vision, weight loss, recurrent infections, and tiredness are not usually severe and may be absent.

• Risk factors for type 2 diabetes, including a strong family history, obesity, or Black or Asian family origin.
• Evidence of insulin resistance, for example the skin appearance of acanthosis nigricans.

Diabetes is usually diagnosed by an HbA1c of 48 mmol/mol (6.5%) or more. If the use of HbA1c is inappropriate (for example in people with end-stage chronic kidney disease), type 2 diabetes is diagnosed by a fasting plasma glucose level of 7.0 mmol/L or greater.

In an asymptomatic person, the diagnosis of diabetes should never be based on a single abnormal HbA1c or fasting plasma glucose level; at least one additional abnormal HbA1c or plasma glucose level is essential. If the second test results are normal, it is prudent to arrange regular review of the person.

In a symptomatic person, diabetes can be diagnosed with more confidence on the basis of a single abnormal HbA1c or fasting plasma glucose level (although a second test may be prudent).

Type 2 diabetes is more likely in a person with:

• No additional features of type 1 diabetes. These include; rapid onset, often in childhood, insulin dependence, and ketoacidosis.
• No features of monogenic diabetes or diabetes secondary to a pathological condition or disease, drug treatment, trauma, or pancreatic surgery.

How do I diagnose type 2 diabetes in children

Consider the diagnostic possibility of type 2 diabetes in a child or young person who presents with:

• Persistent hyperglycaemia (random plasma glucose more than 11 mmol/L). Be aware that the characteristic features of thirst, polyuria, blurred vision, weight loss, recurrent infections, and tiredness are not usually severe and may be absent.
• Risk factors for type 2 diabetes including a strong family history, obesity, or Black or Asian origin).
• Evidence of insulin resistance for example the skin appearance of acanthosis nigricans.
• No additional features of type 1 diabetes
• No features of monogenic diabetes or diabetes secondary to a pathological condition or disease, drug treatment, trauma, or pancreatic surgery.

If type 2 diabetes is suspected, refer the child or young person immediately (on the same day) to a multidisciplinary paediatric diabetes care team with the competencies needed to confirm the diagnosis and provide immediate care.

Pitfalls of HbA1c testing

It is important to consider the pitfalls of HbA1c testing in the following situations.

HbA1c should not be used to diagnose diabetes mellitus in the following groups:

• Children and young people, that is younger than 18 years of age.
• Pregnant women or women who are two months postpartum.
• People with symptoms of diabetes for less than 2 months.
• People at high diabetes risk who are acutely ill – for example who have a current infection.
• People taking medication that may cause hyperglycaemia – for example corticosteroids.
• People with acute pancreatic damage, including pancreatic surgery.
• People with end-stage chronic kidney disease.
• People with HIV infection.

HbA1c should be interpreted with caution in people with:

• Abnormal haemoglobin.
• Anaemia
• Altered red cell lifespan, for example post-splenectomy.
• A recent blood transfusion.

How should I diagnose diabetic ketoacidosis?

Diabetic ketoacidosis (DKA) is the metabolic state characterised by the triad of marked hyperglycaemia, acidosis, and ketonaemia. It is a medical emergency because it leads to dehydration and electrolyte imbalances. Although more common in type 1 diabetes, people with type 2 diabetes can also develop DKA.

Symptoms of diabetic ketoacidosis (DKA) include:

• Increased thirst and urinary frequency.
• Weight loss.
• Inability to tolerate fluids.
• Persistent vomiting and/or diarrhoea.
• Abdominal pain.
• Lethargy and/or confusion.

Signs of DKA include:

• A ‘fruity’ smell, which is caused by the excretion of the ketone acetone on the breath.
• Acidotic breathing — deep sighing (Kussmaul) respiration.
• Dehydration, which can be classified as:

Mild — only just clinically detectable.

Moderate — dry skin and mucus membranes; reduced skin turgor.

Severe — sunken eyes and prolonged capillary refill time.

Shock — the person is severely ill with:

– Tachycardia, poor peripheral perfusion, and (as a late sign) hypotension (indicating decreased cardiac output).

– Lethargy, drowsiness, or decreased level of consciousness (indicating decreased cerebral perfusion).

– Reduced urine output (indicating decreased renal perfusion).

Suspect DKA in a person with known diabetes or significant hyperglycaemia, which is detected by finger-prick blood glucose level greater than 11 mmol/L and the following:

Clinical features of DKA (outlined above)

Precipitating factors, such as:

• Infection
• Physiological stress, including trauma or major surgery.
• Inadequate insulin or non-adherence with insulin treatment.
• Other medical conditions, such as hypothyroidism or pancreatitis.
• Drugs, including corticosteroids, diuretics, and sympathomimetic drugs [for example salbutamol]).

Ketones in the urine or blood.

• In an adult with suspected DKA, test for urine or blood ketones, even if plasma glucose levels are near-normal.
• In a child or young person with suspected DKA, test for blood ketones using a ketone testing meter and strips, even if plasma glucose levels are near-normal. If this is not possible, arrange immediate admission to a hospital with acute paediatric facilities.
• Ketones are high if above 2+ in the urine or above 3 mmol/L in the blood.

Consider the possibility of DKA in all people with type 2 diabetes who are unwell, bearing in mind that:

• Low blood ketone levels (less than 3 mmol/L) do not always exclude DKA.
• Hyperglycaemia may not always be present — children and young people on insulin therapy may develop DKA with normal blood glucose levels.

How do I diagnose hypoglycaemia?

Hypoglycaemia (low blood glucose) is defined as when blood glucose levels are lower than 3.5 mmol/L.

The severity of hypoglycaemia is defined by the clinical manifestations:

• Mild hypoglycaemia presents with a wide variety of symptoms, including hunger, anxiety or irritability, palpitations, sweating, or tingling lips.
• As the blood glucose levels fall, the person may experience weakness and lethargy, impaired vision, and confusion or irrational behaviour. Cognitive function deteriorates when blood glucose levels fall below 3.0 mmol/L.
• Severe hypoglycaemia may result in convulsions, loss of consciousness, and coma. People with severe hypoglycaemia are unable to self-manage a hypoglycaemic episode and require help from another person to achieve normal blood glucose levels.

Summary

During this module you have learnt how to

Make a diagnosis of type 2 diabetes in adults, and know when to suspect type 2 diabetes in a child or young person

When to suspect diabetic ketoacidosis

When to suspect hypoglycaemia

Audit activities

Is everyone with a diagnosis of diabetes recorded on the practice diabetes register?

What percentage of people registered with diabetes are:

a) offered a structured education course? And

b) Attend

Resources

Prodigy Patient – information for patients, available as an app or online, at https://www.prodigy-patient.co.uk

Holt T, Kumar S. ABC of Diabetes. In: Holt T, Kumar S. (Eds) Types of Diabetes. Wiley-Blackwell Publication. 2010;5, 5-8.

Kilpatrick E, Atkin S. Using haemoglobin A(1c) to diagnose type 2 diabetes or to identify people at high risk of diabetes BMJ 2014;348:g2867

NICE QS125. Diabetes in children and young people,2016

https://www.nice.org.uk/guidance/qs125

NHS Diabetes, Diabetes UK, Department of Health. National Service Framework for Children, Young People and Maternity Services. Diabetes Type 1 in childhood and adolescence, 2010. https://www.gov.uk/government/publications/diabetes-type-1-in-childhood-national-service-framework-for-children-young-people-and-maternity-services

NICE CG127. Hypertension. Clinical management of primary hypertension in adults, 2011 (Updated 2016). https://www.nice.org.uk/guidance/cg127

NICE QS26. Diabetes in adults, 2011 (Updated 2016) https://www.nice.org.uk/guidance/qs6

NICE NG18. Diabetes (type 1 and type 2) in children and young people: diagnosis and management,2015 (Updated 2016). https://www.nice.org.uk/guidance/ng18

NICE NG17. Type 1 diabetes in adults: diagnosis and management, 2015 (Updated 2016). https://www.nice.org.uk/guidance/ng17

NICE NG28. Type 2 diabetes in adults: management (full guideline), 2015. https://www.nice.org.uk/guidance/ng28/evidence/full-guideline-pdf-78671532569