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Type 1 Diabetes: Investigations and Monitoring with blood and urine tests
Scope
Monitoring to assess cardiovascular risk and renal function as recommended by NICE.
Non-fasting blood tests are usually sufficient to monitor lipids.
Out of scope
Although some GPs measure FBC, LFTs, B12 and folate there is not a good evidence base for doing this routinely. Rarely an unexpected drop in HbA1c will be due to anaemia. Liver transaminases (ALT or AST) should be measured prior to starting a statin, and again after 3 and 12 months. Long term monitoring of LFTs is not indicated
This guidance does not cover other aspects of diabetes monitoring such as retinal screening and foot examination
At Diagnosis
- Blood - FBC, Renal, ALT or LFT if single test not available, HbA1C, non- fasting lipid profile (total cholesterol, HDL cholesterol, non-HDL cholesterol and triglycerides), TSH, Coeliac antibodies
- Urine - Albumin : Creatinine Ratio
Annually
- Blood - Renal, HbA1C, non-fasting lipid profile (total cholesterol, HDL cholesterol, non-HDL cholesterol and triglycerides), TSH
- Urine - Albumin : Creatinine Ratio
Every 3-6 months
- Blood - HbA1c
Limitations of HbA1c
- Rapid onset of diabetes – an increase in HbA1c may not be detected until a few weeks later
- Suspected type 1 diabetes - rapid onset of symptoms, weight loss, ketosis
- Children - because most will have type 1 diabetes
- Steroids - Antipsychotics & immunosuppressants can raise blood glucose, rarely precipitously
- After pancreatitis or pancreatic surgery
- Pregnancy - Multiple factors make HbA1c lower in pregnancy
- Conditions with reduced red cell survival may lower HbA1c markedly
- Haemoglobinopathy which will normally be detected by the lab, but should be suspected in racial groups where there is a high prevalence of sickle trait, sickle disease or thalassaemia.
- Haemolytic anaemia
- Severe blood loss
- Splenomegaly
- Antiretroviral drugs
- Increased red cell survival may increase HbA1c e.g. splenectomy.
- Renal dialysis patients have a markedly reduced HbA1c especially if treated with erythropoietin.
- Iron and B12 deficiency and their treatment. May raise or lower HbA1c.
Evidence
Type 1 diabetes in adults: diagnosis and management. NICE guideline [NG17]. Published: August 2015
Lipid modification: cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease. NICE guideline [CG181]. Published: July 2014.
Pathway Group
This guideline has been signed off by Pathology Optimisation Clinical Group on behalf of NHS Devon.
Publication date: June 2017
