Indian Write- Ups

Management

Interpretation of Blood Glucose Results

- Dr. Alka Ganesh

Christian Medical College Hospital, Vellore.

Pre Prandial Glucose

Pre meal glucose estimations are used only in inpatient practice, and when the patient is practicing home monitoring (SMBG-Self monitoring of blood glucose) with the help of a glucometer. If pre meter values are high, say 200mg%, then the soluble insulin does is increased, or the interval between insulin injection and the meal is increased by 10-15 minutes.

Random Glucose

The random glucose level has no value in assessment of diabetic control unless details of preceding meal and insulin therapy is known. The random sample is an invaluable too, however, in an emergency situation such as coma, convulsions, disorientation and dizziness, to detect whether the glucose level is the causative factor or not. In the detection of diabetes, a random plasma glucose sample = 200mg plus classic signs and symptoms of diabetes mellitus including Polydipsia, Polyuria, Polyphagia and weight loss is diagnostic.

Interpretation of Blood Glucose for Insulin Adjustment

This can be done if the time of action of short and intermediate insulins is known. Short acting insulins action peaks at 2 hours and is over by 5-8 hours.

Intermediate acting insulin action peaks at 8 hours and lasts upto 24 hours.

A few examples of insulin does adjustment on the basis of blood glucose values

In Example I Scenario A, all glucose values are high including the post lunch value which is the period of peak action of Human Monotard. Therefore the Human Monotard and Human Actrapid doses are increased.

In Example I Scenario B, the glucose level at the time of peak insulin action is low; hence a further increase of Human Monotard to control fasting glucose will cause hypoglycaemia. Hence, the morning Human Monotard is decreased and a second dose of Monotard is added at night to reduce the fasting glucose.

In Example II Scenario A, all daytime values are high, so breakfast and lunch doses are increased. Since the 3AM value is low, evening Human Monotard cannot be increased to bring down fasting glucose. This difficulty can be circumvented by increasing Human Monotard marginally, and adding a late night snack to prevent hypoglycaemia.

In Example II Scenario B, daytime values are under control, but evening glucose values are high, so evening Human Actrapid alone is increased.

Example II
	Insulin Dose (Units)		Glucose Values (mg%)			Insulin adjustment (Units)
			Timing	A	B	Insulin	A	B
Breakfast	Human Monotard	10	Fasting	300	100	Human Monotard	15	10
	Human Actrapid	10	2hr. post			Human Actrapid	15	10
			breakfast	350	180

Lunch	Human Actrapid	10	Pre lunch	250	150	Human Actrapid	15	10
			Post lunch	400	200

Dinner	Human Monotard	4	Pre dinner	150	200	Human Monotard	10	4
	Human Actrapid	4	Post Dinner	200	350	Human Actrapid	4	10
			3AM	80	150	(Late Night Snack)

Assessment of Metabolic Control

Though a glucose profile is invaluable in indicating insulin changes, by its very variability, glucose levels do not indicate over all glycaemic control. The glycosylated hemoglobin level is useful in this respect and is a retrospective assessment over the proceeding 3 months.

However, the HbA1c cannot indicate how to adjust the insulin dosage, so blood glucose sampling is also required. It would be very useful to have a continuous recording or at least, an instantaneous reading of blood glucose. Much research is ongoing to produce a glucose sensor which can be implanted in tissues and there have been remarkable success. However, implanted glucose sensors have a short life and are not yet a part of daily diabetic management; perhaps they will be in the 21st century.

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