Diabetes Tests and Diagnosis

Diabetes is usually split into 2 types plus gestational diabetes

Daibetes type 1, where the body's immune system attacks and destroys the cells that produce insulin.
  • Affects all ages,
  • Normally requires insulin.
Diabetes type 2, where the body doesn't produce enough insulin, or the body's cells don't react to insulin.
  • Maturity onset, usually over 40,
  • Strong familial link,
  • A history of high blood pressure increases the risk.
  • Type II is usually diet and tablet controlled.
  • Weight can be critical.
  • 2-4 x More common in South Asian descent, African-Caribbean and Black African descent.

During pregnancy, some women have such high levels of blood glucose that their body is unable to produce enough insulin to absorb it all. This is known as gestational diabetes. Often corrects after delivery.

 

    Insulin is what the body produces to control the levels of Glucose, the principle simple carbohydrate sugar used to produce energy. Without healthy insulin, the levels of Glucose become high, causing multiple health problems.

    • 90% of diabetes in the UK is type 2
    • 3.6 million people have clinical Diabetes in the UK. (end 2017)

    Pre-Diabetes

    Many more people have blood sugar levels above the normal range, but not high enough to be diagnosed as having clinical diabetes.

    This is sometimes known as pre-diabetes. If your blood sugar level is above the normal range, your risk of developing full-blown diabetes is increased. Other risk factors which make this likely are strong family history and obesity.

    Most pre-diabetes is symptom free with up to 10 years elapsing before clinical diabetes is diagnosed.

    It's very important for diabetes to be diagnosed as early as possible because it will get progressively worse if left untreated.

    What is a normal blood glucose level ?

    Nice give the following guidance levels

    • Between 4.0 to 5.4 mmol/L (72 to 99 mg/dL) when fasting 
    • Up to 7.8 mmol/L (140 mg/dL) 2 hours after eating
    In the UK we use the mmol/L scale for recording blood glucose levels. Other countries use mg/dL, so we quote both above.

     

    How to test for high glucose levels ?

    Measuring a blood sugar level is easy using a finger prick sample of blood. There are a range of digital meters with glucose test strips which will measure the exact blood glucose level for you. These blood glucose meter packs allow repeat testing, which will probably be a good idea over a 6-18 month period.

    The table below gives  a guide to normal glucose levels in healthy adults and what you could get in pre-diabetes and full blown diabetes. Fasting means not eaten or drank for 12 hours, and post-prandial refers to tests taken 2 hours after a large main meal.

    Normal Prediabetes Diabetes
    Fasting Below 5.5 mmol/l 

    5.5 to 6.9 mmol/l  7.0 mmol/l or more 
    2 hour post-prandial Below 7.8 mmol/l 

    7.8 to 11.0 mmol/l 

    11.1 mmol/l or more

     

    Other ways to test for Diabetes.

    Not everyone likes the idea of finger prick blood tests, especially if you are screening without symptoms. There is another way, its not as precise, but can be used as an indicator to proceed to blood testing. 

    In healthy adults there should be no glucose normally detectable in urine dip testing. The kidneys are designed not to leak or waste valuable glucose, but they become overloaded as the blood levels increase above 7.8

    At this point glucose traces start to become detectable in urine and rise in line with peaks in blood glucose levels. Urine Reagent Testing strips for glucose are able to detect this glucose and recurrent glucose in urine can be an indicator of both pre and clinical diabetes.

    Glucose pads are included on most urine testing strips used to screen in NHS and GP clinics. They are also available in single pad format for specifically screening for diabetes. You can easily do these test yourself at home, screen both fasting and post prandial urine samples.

     

    Oral Glucose Tolerance  Test (OGTT)

    An OGTT is a hospital or out-patient test and involves first taking a fasting sample of blood and then taking a very sweet drink containing 75g of glucose.

    After having this drink a further blood blood glucose sample is taken after 2 hours.

    (do not confuse glucose with houshold sugar)

    HbA1c test for diabetes diagnosis

    HbA1c is the preferred diagnostic test for diabetes in the UK as it can be taken at any time of day and effectively looks back over a long period of time for high glucose.

    Glycoslated haemoglobin is caused by high blood glucose so the HbA1c test does not directly measure the level of blood glucose, but looks at how much glycosated haemoglobin your blood contains. The test is influenced by how high or low your blood glucose levels have tended to be over a period of 2 to 3 months before the test is taken. It is a hospital laboratory test currently but a point of care test is in development.

    Indications of diabetes or prediabetes are given under the following conditions:

    • Normal: Below 42 mmol/mol (6.0%)
    • Prediabetes: 42 to 47 mmol/mol (6.0 to 6.4%)
    • Diabetes: 48 mmol/mol (6.5% or over)