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Diabetes Mellitus Type 2Published by: Domus Medica | SSMGLast published: 2017Diabète sucré de type 2Published by: SSMG | Domus MedicaLast published: 2017

Type 2 diabetes is most often diagnosed on routine screening.

Strong risk factors, which also indicate the need for screening, include: older age; overweight/obesity; certain ethnic groups (including black, South Asian, or Hispanic ancestry); family history of type 2 diabetes; history of gestational diabetes; presence of non-diabetic hyperglycaemia; polycystic ovary syndrome; hypertension; dyslipidaemia; or known cardiovascular disease.[27][34]

Symptomatic patients may present with fatigue, polyuria, polydipsia, polyphagia, or weight loss (usually when hyperglycaemia is more severe [e.g., >16.6 mmol/L, >300 mg/dL]); blurred vision; paraesthesias; skin infections (bacterial or candidal); urinary tract infections; or acanthosis nigricans.[Figure caption and citation for the preceding image starts]: Acanthosis nigricans involving the axillaFrom the collection of Melvin Chiu, MD; used with permission [Citation ends].com.bmj.content.model.Caption@123a4a53 ​The presence of symptoms may indicate more overt hyperglycaemia.

Diagnosis

Use the World Health Organization criteria to establish a firm diagnosis of diabetes in a non-pregnant adult:[68] 

  • Fasting plasma glucose ≥7.0 mmol/L (≥126 mg/dL), or

  • Plasma glucose ≥11.1 mmol/L (≥200 mg/dL) 2 hours after 75 g oral glucose, or

  • Glycosylated haemoglobin (HbA1c) ≥48 mmol/mol (≥6.5%), or

  • In a symptomatic patient, random plasma glucose of ≥11.1 mmol/L (≥200 mg/dL).

Do not diagnose diabetes in an asymptomatic person based on a single test result.

  • A repeat confirmatory test on a subsequent day is required in asymptomatic patients.[69]​ 

  • In practice, a repeat test is often required in patients with mild-to-moderate symptoms, while a patient with severe symptoms and elevated test results does not usually need a repeat test.

Check urine ketones at diagnosis if the patient is symptomatic of hyperglycaemia (polyuria, polydipsia, weakness) and volume depletion (dry mucous membranes, poor skin turgor, tachycardia, hypotension, and, in severe cases, shock). Continue to monitor throughout the course of disease.

  • If increased ketone levels are left untreated, they can lead to progressive dehydration and diabetic ketoacidosis (DKA). DKA is a severe, life-threatening complication of diabetes. More commonly seen in people with type 1 diabetes, DKA may also occur in people with type 2 diabetes, particularly:[70][71][72][73]​ 

    • In the presence of an underlying infection or other stressors

    • Following cardiovascular events, malignancy, antipsychotic medication, and concomitant treatment with sodium-glucose cotransporter-2 (SGLT2) inhibitors.

  • See Diabetic ketoacidosis.

At initial diagnosis of diabetes, it is important to determine whether immediate treatment with insulin is required (if an adult with type 2 diabetes is symptomatically hyperglycaemic, rescue therapy of insulin or a sulfonylurea should be considered).[36]​​

It is also important to distinguish between type 1 and type 2 diabetes, because these conditions are treated differently.[74] Some individuals cannot be clearly classified as having type 1 or type 2 diabetes at the time of diagnosis.[34][68]

  • Initial classification of the diabetes subtype should be based on clinical grounds.[74]

    • Type 1 diabetes can occur at any age but tends to be diagnosed in younger (aged <35 years), thinner people, and has a more rapid onset and often more severe symptoms than type 2 diabetes.

    • No single clinical feature is sufficient to make a diagnosis by itself.[74] For example, the average BMI of those with type 1 diabetes is increasing, and the age at which people are diagnosed with type 2 diabetes is decreasing, making it important that average BMI and age are not used in isolation to make a diagnosis.[74]

  • The National Institute for Health and Care Excellence (NICE) recommends that following an initial diagnosis of type 1 diabetes, adults should have diabetes-specific autoantibodies measured.[74] A false-negative result is lowest at the time of diagnosis.[74] Further, a false negative rate can be reduced by carrying out quantitative tests for 2 different diabetes-specific autoantibodies (with at least 1 being positive).[74]

    • Autoantibodies to glutamic acid decarboxylase 65 (GAD), islet cell antibodies (ICA), insulin antibodies, antibodies to tyrosine phosphatase-related islet antigen-2 (IA-2 and IA-2beta), and zinc-transporter-8 antibodies (ZnT8) can help to identify individuals with immune-mediated diabetes (the most prevalent form of type 1 diabetes), although these antibodies fade with time after onset of illness.[34][75][76][77]

  • Routine serum C-peptide measurement should not be used to confirm type 1 diagnosis; however, if a negative diabetes-specific autoantibody result is obtained, or if diabetes classification remains uncertain at a subsequent visit, serum C-peptide measurement could be considered.[74]

    • If C-peptide testing is indicated, bear in mind that it has better discriminative value the longer the test is done after initial presentation.[74]

    • In clinical practice, serum C-peptide testing can be paired with blood glucose.[74]

  • If a patient has received an initial diagnosis of type 2 diabetes, but has persistently/significantly raised HbA1c despite oral medication or has persistent osmotic symptoms/weight loss, consider testing for autoantibodies, as the patient may have type 1 diabetes. The patient may have been wrongly diagnosed with type 2 diabetes.

Evaluation of disease and risks of macrovascular/microvascular complications

Assess the patient’s blood pressure, smoking status, and fasting lipid levels.

Take baseline urine albumin/creatinine ratio and serum creatinine with estimated glomerular filtration rate readings, because signs of chronic kidney disease may be present at diagnosis.[34]

Check liver function tests. Metabolic dysfunction-associated steatotic liver disease (MASLD) (also known as non-alcoholic fatty liver disease) is more common in people who have type 2 diabetes. The American Diabetes Association (ADA) recommends screening all patients with type 2 diabetes or pre-diabetes for clinically significant fibrosis (defined as moderate fibrosis to cirrhosis) secondary to MASLD using a calculated fibrosis-4 (FIB-4) index (derived from age, alanine aminotransferase [ALT], aspartate aminotransferase [AST], and platelet count).[78] [ Cirrhosis probability in hepatitis C (FIB-4) Opens in new window ] ​​​ Patients with an indeterminate or high FIB-4 index should have additional risk stratification by liver stiffness measurement with transient elastography, or by measurement of enhanced liver fibrosis (ELF), a blood biomarker.[78]​ NICE recommends using the ELF test in people who have been diagnosed with MASLD to test for advanced liver fibrosis.[79]

The European Society of Cardiology (ESC) advises that all patients with diabetes should be evaluated for medical history and symptoms suggestive of atherosclerotic cardiovascular disease (ASCVD) as part of the cardiovascular (CV) risk assessment.[80]​ Consider whether further assessment of cardiac, carotid, and peripheral circulation (e.g., ECG or vascular investigation, such as an ankle-brachial pressure index) is indicated, especially in those with cardiovascular symptoms.[80] Neither the ESC or the ADA recommends routine screening tests for coronary artery disease in asymptomatic individuals.[34][80]​ The ESC further advises that regular screening for carotid artery disease is not recommended in patients without history of cerebrovascular disease.[80]

Initial and ongoing monitoring

See Monitoring for more detail on ongoing monitoring. 

On diagnosis:

  • Immediately refer the patient to the local eye screening service[36]

  • Assess the patient’s risk of developing a diabetic foot problem; also do this at least annually.[81]​ When foot problems arise, patients should be referred to the foot protection service or a multi-disciplinary foot care service, as appropriate.[81]

  • Measure the patient’s urine albumin to creatinine ratio and continue to check this every year.

  • Measure HbA1c levels; also do this every 3-6 months (tailored to individual needs), until the patient’s HbA1c is stable on unchanging therapy; and every 6 months once the patient’s HbA1c level and blood glucose-lowering therapy are stable.[36]

  • Measure blood pressure; then at least once a year in any adult with type 2 diabetes without previously diagnosed hypertension or renal disease.[82] Offer and reinforce preventive lifestyle advice.[82]

Ensure the patient receives ongoing individualised nutritional advice from a healthcare professional with specific expertise in nutrition.[36]​​

Aim to include a routine assessment of frailty in reviews for older people with diabetes.[83][84][85]​ Use a validated tool (e.g., the electronic Frailty Index [eFI], the Rockwood frailty score, or Timed Up and Go) to confirm clinical suspicion of frailty.[84][85]​ Frail patients need a tailored approach to management; de-escalation of therapy is as important as intensification. Consult a specialist if you need guidance. 

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