Biology of Disease

samples are categorized as having impaired fasting glucose (IFG) and are at
risk of developing diabetes. The values given relate to venous plasma samples
and are different from those for whole blood samples.

The management of diabetes mellitus aims to provide relief from symptoms
and reduce the chances of developing acute and chronic complications. This
includes educating the patient that diabetes is a life-long disease and affected
individuals must be responsible for their own treatment. Regular clinical and
laboratory assessment of the patient is required to ensure that treatment is
effective, to detect early signs of treatable complications so as to reduce their
progression and ensure compliance with treatment. Management involves
the dietary restriction of simple sugars and of saturated fats and cholesterol
and the use of complex carbohydrate and fibers. Dietary control is often
accompanied by use of injected insulin or oral hypoglycemic drugs, such
as sulfonylureas, in patients with type 1 and type 2 diabetes respectively.
Occasionally, it may be necessary to use insulin in patients with type 2
diabetes to control blood glucose effectively. Hypoglycemic drugs act by
increasing the sensitivity of A cells to glucose therefore stimulating insulin
release or by increasing sensitivity of target cells to insulin. Both effects will
reduce blood glucose levels. Some hypoglycemic drugs act to reduce the
absorption of glucose by the GIT or reduce glycogenolysis in the liver. Diabetic
patients on treatment are monitored regularly to ensure that blood glucose
is kept in control. Most patients measure their own blood glucose at home
regularly using kit methods based on reagent strips and a portable glucose
meter (Figure 7.26) and adjust insulin dosage according to needs, perhaps
following a change in diet, during illness or after exercise. The amount of
glycated hemoglobin (Figure 1.14) in a patient is determined regularly to
assess therapy compliance because its presence is an indicator of average
glycemia over the previous 6–8 weeks. The amount of glycated hemoglobin
tends to be less than 6% in nondiabetics but may exceed 10% in uncontrolled
diabetes. Diabetic patients with high values have poor blood glucose control
and their treatment or compliance must be reviewed.

Hypoglycemia

Hypoglycemia is defined as a blood glucose concentration less than 2.2
mmol dm–3 in a random specimen collected into a tube containing an
inhibitor of glycolysis. Hypoglycemia occurs because of an imbalance
between glucose intake, endogenous glucose production and glucose

REGULATION OF BLOOD GLUCOSE

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Meter

Carrying case

Holder for lancets to

draw blood samples

Strips for testing

glucose

Control solutions of

high and low glucose

concentrations

Figure 7.26 A blood glucose meter.