Monitoring the control of diabetes

Urine tests:

Simple to perform using a dipstick and it can usually be assumed that a patient with consistently negative tests and no symptoms of hypoglycaemia is fairly well controlled.

It should be noted that the correlation between urine tests and blood glucose is poor for 3 reasons:

1. Changes in urine glucose lag behind changes in blood glucose
2. The mean renal threshold is ~10mmol/L but the range is wide (it also increases with age)
3. Urine tests can give no clear guidance concerning blood glucose levels below the renal threshold

Blood glucose testing:

• Provides the best assessment of day-to-day control
• Patients are taught to record their own blood glucose profiles using finger-prick blood samples with reagent strips.
• Blood should be taken from the side of a fingertip, NOT the tip (which is densely innervated) using a special lancet.

Glycosylated haemoglobin (HbA₁ or HbA_1c) and fructosamine:

Glycosylation of Hb occurs as a two-step reaction, resulting in the formation of a covalent bond between the glucose molecule and the terminal valine of the Β-chain of the Hb molecule.

Glycosylated Hb is expressed as a percentage of the normal Hb (normal is 4-8%)

Glycosylated plasma proteins (‘fructosamine’) may also be measured as an index of control.

These measurements provide us with a good impression of long-term glycaemic control.

What should be checked at each visit?

• Review of self-monitoring results and current treatment
• Talk about targets and change where necessary
• Talk about any general or specific problems
• Continued education

These should be checked at least once a year:

• Biochemical assessment of metabolic control (e.g. glycosylated Hb test)
• Measure bodyweight
• BP
• Plasma lipids
• Visual acuity
• Examine state of retina
• Renal function tests (e.g. creatinine, proteinuria)
• Check condition of feet, pulses and neurology
• Review CVS risk factors
• Review self-monitoring and injection techniques
• Review eating habits