Diabetes-Carmarthenshire

Useful definitions

Identifying people with previously undiagnosed diabetes

Management of pre-diabetes states

 

Useful definitions

Diabetes

• Diagnosed when either random plasma glucose > 11 mmol/l, or fasting plasma glucose > 7 mmol/l, on one occasion if symptoms of diabetes are present, or on two separate occasions if no symptoms of diabetes are present

Impaired glucose tolerance (IGT)

• Fasting plasma glucose <7mmol/l, but 2 hour post-prandial glucose load value between 7.8-11.0mmol/l

Impaired fasting glucose (IFG)

• Fasting plasma glucose level between 6.1-6.9 mmol/l

Type 1 diabetes

• Diabetes in which there is a loss of the body's ability to produce insulin. This is associated with the production of ketones , a high level of which causes ketoacidosis . The onset tends to be quite rapid. Insulin treatment is mandatory and life-saving. Type 1 diabetes can also be diagnosed in retrospect in those patients under the age of 40 who have gone on to treatment with insulin within 12 months of initial presentation. Type 1 diabetes used to be known as Insulin Dependant Diabetes, IDDM or Juvenile Onset Diabetes.

Type 2 diabetes

• Diabetes in which the body can still make some insulin, but not enough, or when the insulin that is produced cannot work properly (insulin resistance). Because there is still insulin present, ketones are not produced and ketoacidosis does not occur . Treatment can be by diet, tablets or insulin. Type 2 diabetes used to be known as Non-insulin Dependant Diabetes, NIDDM or Maturity Onset Diabetes.

Secondary diabetes

• Diabetes caused by some other mechanism, e.g. drugs (steroids, growth hormone, thiazide diuretics), pancreatic disease (cancer, pancreatitis), genetic syndromes (porphyria, haemachromotosis, thalassaemia), other endocrine conditions (Cushings, acromegaly, thyrotoxicosis, phaeochromocytoma).

HbA1c

• The percentage of haemoglobin in the blood that has glucose attached to it. This provides a measure of how good diabetic control has been over the preceding 3 months. Good diabetic control is considered to produce an HbA1c of less than 7%.

Microalbuminuria

• A urine albumin level of > 30mg/l from an overnight urine sample, or a urine albumin:creatine ratio of >3.0

 

Identifying people with previously undiagnosed diabetes

Background

• Many people are unaware that they have diabetes, either because they have no symptoms or because they misinterpret the classical diabetic symptoms of lethargy, thirst, polydipsia and polyuria.

• Early diagnosis and treatment is likely to reduce the risk of diabetic complications.

• Currently the preferred method of detecting diabetes in these people is through opportunistic screening , ie testing for diabetes when people are in contact with health services for another reason.

 

Who to test

• A fasting venous plasma glucose should be requested in all adults aged >40 years in the following at risk groups:
  -family history of type 2 diabetes
  -established ischaemic heart disease
  - hypertension
  - body mass index >30
  - Asian or Afro-Caribbean ethnic groups
  - previous gestational diabetes or large baby

• If fasting glucose is >7.0 mmol/l diabetes is confirmed

• If fasting glucose is 6.1-6.9 mmol/l then arrange an oral glucose tolerance test (OGTT)

• For an OGTT measure venous plasma glucose fasting and 2h following 75g glucose taken orally:
  - if 2h glucose >11.0 mmol/l diabetes is confirmed
  - if 2h glucose is 7.8-11.0 mmol/l, impaired glucose tolerance (IGT) is present
  - if fasting glucose is 6.1 - 6.9 mmol/l the patient has impaired fasting glycaemia (IFG)

 

Diagnostic cautions

• Fasting glucose requires a certainty of no previous calorie intake, ie nothing to eat and only water to drink

• The above values apply to venous plasma glucose; fasting capillary blood glucose is around 1.0 mmol/l lower

• Diagnostic procedures should not be performed in the presence of acute illness

• Interpret results with reservation in people on blood glucose raising drugs

 

Management of pre-diabetes states

• IGT and IFG are pre-diabetes states which are associated with an increased risk of macrovascular disease as well as a 10% annual risk of progression to frank diabetes.

• Give advice on diet, exercise, weight management and smoking (see the Lifestyle Management section)

• Assess for the presence of other cardiovascular risk factors and manage appropriately

• Provide a Read code and enter onto the computer for regular follow up as well as onto a register for people with pre-diabetes

• Arrange regular OGTT's to detect type 2 diabetes if it does develop. Diabetes UK currently recommends repeating the test every 3 years. In addition, annual lipid and blood pressure readings should be measured, and lifestyle advice should be offered annually. A decision should be made within the practice team as to the best way to organise this e.g. standard appointments, or through the diabetic clinic.