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GEM - diabetes - the basics part one

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Some basic concepts in diabetes.

Scenario A) A 54 year old man with a history of hypertension recently joined your patient list. As part of his new patient medical, the practice nurse requested blood tests as part of the practice hypertension protocol. The fasting glucose requested had a result of 6.5 mmol/l.

  • why is this level of blood glucose significant (what definition does it satisfy)?
  • what is the significance in terms of future diabetes risk

If this gentleman had a subsequent oral glucose tolerance test and the 2 hour glucose result was 8.5 mmol/l then what definition does this satisfy? In the context of the previous definition, what is the future risk of development of diabetes?

If there is a family history of type 2 diabetes, is there a significant risk of a family member developing type 2 diabetes

At patients at high risk of development of type 2 diabetes, which intervention (metformin, conventional advice, intensive lifestyle modification) was the most effective in prevention of development of type 2 diabetes

Diagnosis of Diabetes

Scenario B) A 64 year old man with a history of hypertension was reviewed by the practice nurse as part of a QOF review. His BMI was recorded as 33.1 and blood pressure was 145/90 mmHg. His hypertension bloods were requested as per practice protocol and a fasting glucose result revealed a blood glucose of 9.1 mmol/L. He had no symptoms of polyuria or polydipsia. His weight had remained unchanged for several months.

  • is a fasting glucose of > 7 mmol/L on a single occasion enough to satisfy the diagnostic criteria for diabetes?
  • is HbA1C part of the diagnostic criteria for diabetes?

Scenario C) A 54 year old woman has a history of previous gestational diabetes diagnosed during 2 of her 3 pregnancies. She has had symptoms of polyuria and polydipsia noted for the last month. She has a BMI of 31. Her urine was dipsticked in the GP surgery and revealed +++ glucose but no ketones. A random BM in surgery was 11.4. A fasting glucose was then requested which was raised at 9.2 mmol/l and a diagnosis of type 2 diabetes was made.

  • why in this case is a single fasting glucose sufficient for diagnosis?
  • if a random value is used for diagnosis of diabetes, should this be a venous sample?
  • why is the history of gestational diabetes important with respect to subsequent development of type 2 diabetes?

Management of Type 2 Diabetes

General Points

In general, after the diagnosis of type 2 diabetes is made, initial management is dietary for the first three months. If, after this period, glycaemic control is unsatisfactory (HBA1C> 7%) then oral hypoglycaemic agents are indicated. However if, at time of diagnosis, the fasting glucose is >= 13mmol/L (and the usual diet for the patient does not have excessive sugar) then it is likely that the patient will require oral hypoglycaemic agents (as well as dietary advice) from the onset of management (1). In general the first-line agent for type 2 diabetes is metformin.

The primary care clinician should be aware of the possible insulin deficient type 2 diabetic patient. This patient will not be overweight. If there are no features of type 1 diabetes (e.g. ketonuria) then this patient will require early intervention with medication. In this case the first-line agent is a sulphonylurea. Also the primary care clinician should be aware that this patient may require earlier intervention with insulin than the usual phenotypic type 2 diabetic.

Diet in diabetes

Dietary modification in diabetes involves maintaining a higher intake of complex carbohydrates (with a low glycaemic index) rather than simple carbohydrates.

What is the glycaemic index?


Improving glycaemic control:

In general, metformin is the first-line oral hypoglycaemic medication in type 2 diabetes.

  • how does metformin work?
  • why is metformin used with caution with renal impairment?at what level of renal impairment do NICE state metformin should not be used?
  • how can GI side effects be minimised when intiating metformin?

Monitoring Treatment

Day to Day variation in blood sugar

Is there trial evidence of advantage of blood sugar monitoring compared to urine testing for type 2 diabetics?

Blood sugar testing is often initiated in primary care once a patient has started medication

If blood sugar testing is employed then is the "ideal" pre-breakfast (fasting glucose) reading suggested by JBS2

Long-term sugar control

This is generally measured via the use of glycosylated haemoglobin (HbA1c). What is the basis of the measurement (and timing of measurement) of HbA1c?

How would HbA1c be affected if a patient had haemolytic anaemia?

There is data relating HbA1c to the mean plasma glucose

It is important to be aware of the findings of the UKPDS study.

This study provided evidence regarding the link between glycaemic control and microvascular disease. More recent data provides evidence of a link between macrovascular disease and glycaemic control

What is the target level for HbA1c?

Further oral glycaemic medication following metformin

Metformin is considered the first-line oral hypoglycaemic for type 2 diabetes and is titrated to 1g bd if tolerated. If glycaemic control is still suboptimal then the primary clinician has various choices in terms of other agents to employ:

  • sodium glucose co-transporter 2 (SGLT2 ) inhibitors affect the renal excretion of glucose in their improvement in glycaemic control
  • sulphonylureas (SUs) are effective in lowering blood glucose but frequently result in weight gain and may cause hypoglycaemia. Other side-effects are uncommon. Use of a once daily agent may improve concordance
  • prandial glucose regulators (PGRs) are similar to SUs and, usually in combination with metformin, may be useful in those whose mealtimes are irregular
  • acarbose (50 - 200 mg tds) may be used as triple therapy with metformin and an SU but is frequently poorly tolerated
  • glitazones may be used in combination with metformin or an SU, although triple therapy with metformin and an SU is widely used. Glitazones may also have a special role in patients with metabolic syndrome indicating early use. Glitazones may cause fluid retention and are contraindicated when there is a risk of heart failure, also when hepatic function is compromised
  • gliptins - may be used in combination with SUs or metformin. Glitpins (with appropriate license recommendations) may be used in combination with both SUs and metformin
  • incretin mimetics - as well as a treatment for type 2 diabetes, use of these agents may result in weight loss


  1. Personal Communication (October 12th 2006). Aresh Anwar, Consultant Diabetologist, University Hospitals Coventry and Warwickshire.
  2. Royal College of General Practitioners. Curriculum Statement 15.6 Metabolic Problems.

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