Diagnostic Tests
Results
- mmol/L (≥126 mg/dL) 7.0≤
- 6.5%≤
- mmol/L (≥200 mg/dL) 11.1≤
- mmol/L (≥200 mg/dL) 11.1≤
Tests
-
Fasting plasma glucose ≥7.0 mmol/t (≥126 mg/dL)
- Order after a minimum 8-hour fast. Bear in mind that a repeat confirmatory test is required for diagnosis in most cases.
-
HbA1c ≥6.5%
- Reflects degree of hyperglycaemia over the preceding 3 months.
- Bear in mind that a repeat confirmatory test is required for diagnosis in most cases.
- HbA1c is also used to monitor glycaemic control.
-
2-hour post-load glucose after 75 g oral glucose ≥11.1 mmol/L (≥200 mg/dL)
- Plasma glucose is measured 2 hours after 75 g oral glucose load.
- Bear in mind that a repeat confirmatory test is required for diagnosis in most cases.
-
Random plasma glucose ≥11.1 mmol/L (≥200 mg/dL)
- Non-fasting test. Bear in mind that a repeat confirmatory test is required for diagnosis in most cases.
- Used for rapid assessment of glucose status if symptoms such as polyuria, polydipsia, or weight loss are present.
Screening in General Practice
| Test | Result |
|---|---|
| The fasting lipid profile Dyslipidaemia is common in type 2 diabetes. | May show high LDL, low HDL, and/or high triglycerides |
| Urine ketones 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). | Positive in instances of ketoacidosis |
| Albumin to creatinine ratio (ACR) • Indicates nephropathy and suggests possible other microvascular damage. • Monitored yearly. | May be increased; ACR ≥3 mg/mmol indicates clinically important proteinuria[ |
| Serum creatinine and estimated GFR | May indicate renal insufficiency |
| ECG | May indicate prior ischemia |
| Ankle-brachial pressure index (ABPI) | ≤0.9 is abnormal |
| C-peptide | Normal or high |
| Liver function tests May identify people with non-alcoholic fatty liver disease (NAFLD). | May be elevated |
Screening
The National Institute for Health and Care Excellence (NICE) in the UK recommends that general practitioners should identify people on their practice register who may be at high risk of type 2 diabetes.
Risk assessment should be offered to:
- All adults aged 40 and above (except pregnant women).
- People aged 25 to 39 of South Asian, Chinese, African-Caribbean, and black African ethnicity (except pregnant women).
- Adults with any other condition that increases the risk of type 2 diabetes.
Those with a high risk score should be offered a fasting plasma glucose or HbA1c test; a blood test should be considered regardless of risk score for those aged 25 and over of South Asian or Chinese descent whose body mass index (BMI) is greater than 23 kg/m².
The US Preventive Services Task Force recommends screening for glucose status for adults ages 35 to 70 years who have BMI ≥25 kg/m².
The American Diabetes Association recommends routine screening of non-pregnant asymptomatic adults of any age with BMI 25 or more plus one or more additional risk factors for diabetes.