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

Investigations

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

  1. Rapid onset of diabetes – an increase in HbA1c may not be detected until a few weeks later
    1. Suspected type 1 diabetes - rapid onset of symptoms, weight loss, ketosis
    2. Children - because most will have type 1 diabetes
    3. Steroids - Antipsychotics & immunosuppressants can raise blood glucose, rarely precipitously
    4. After pancreatitis or pancreatic surgery
  2. Pregnancy - Multiple factors make HbA1c lower in pregnancy
  3. Conditions with reduced red cell survival may lower HbA1c markedly
    1. 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.
    2. Haemolytic anaemia
    3. Severe blood loss
    4. Splenomegaly
    5. Antiretroviral drugs
  4. Increased red cell survival may increase HbA1c e.g. splenectomy.
  5. Renal dialysis patients have a markedly reduced HbA1c especially if treated with erythropoietin.
  6. Iron and B12 deficiency and their treatment. May raise or lower HbA1c.

Supporting Information

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 the Pathology Optimisation Clinical Group on behalf of NEW Devon CCG

Publication date: June 2017

 

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