C h a p t e r 3 3
Diabetes Mellitus and the Metabolic Syndrome
805
result in normoglycemia and proper weight gain, and
prevent ketosis.
3
If dietary management alone does not
achieve a capillary blood glucose of 90 to 99 mg/dL or a
2-hour postprandial blood glucose less than 120 mg/dL,
the Fifth International Workshop on GDM recommends
therapy with insulin.
28
More recently, several oral agents
have also been used for the treatment of GDM, includ-
ing glyburide and metformin. Self-monitoring of blood
glucose levels is essential.
Approximately 50% of women with GDM will
develop type 2 diabetes within 5 to 10 years.
26
Women
in whom GDM is diagnosed should be followed after
delivery to detect diabetes early in its course. These
women should be evaluated during their first postpar-
tum visit with a 2-hour OGTT with a 75-g glucose load.
Clinical Manifestations of Diabetes
Diabetes mellitus may have a rapid or an insidious
onset. In type 1 diabetes, signs and symptoms often arise
suddenly. Type 2 diabetes usually develops more insidi-
ously; its presence may be detected during a routine
medical examination or when a patient seeks medical
care for other reasons.
The most commonly identified signs and symptoms
of diabetes are often referred to as the
three polys:
(1)
polyuria (i.e., excessive urination), (2) polydipsia (i.e.,
excessive thirst), and (3) polyphagia (i.e., excessive
hunger). These three symptoms are closely related to
the hyperglycemia and glycosuria of diabetes. Glucose
is a small, osmotically active molecule. When blood
glucose levels are sufficiently elevated, the amount of
glucose filtered by the glomeruli of the kidney exceeds
the amount that can be reabsorbed by the renal tubules;
this results in glycosuria accompanied by large losses
of water in the urine. Thirst results from the intracellu-
lar dehydration that occurs as blood glucose levels rise
and water is pulled out of body cells, including those
in the hypothalamic thirst center. This early symptom
may be easily overlooked in people with type 2 dia-
betes, particularly in those who have had a gradual
increase in blood glucose levels. Polyphagia usually is
not present in people with type 2 diabetes. In type 1
diabetes, it probably results from cellular starvation
and the depletion of cellular stores of carbohydrates,
fats, and proteins.
Weight loss despite normal or increased appetite is a
common occurrence in people with uncontrolled type 1
diabetes. The cause of weight loss is twofold. First, loss
of body fluids results from osmotic diuresis. Vomiting
may exaggerate the fluid loss in ketoacidosis. Second,
body tissue is lost because the lack of insulin forces the
body to use its fat stores and cellular proteins as sources
of energy. In terms of weight loss, there often is a marked
difference between type 2 diabetes and type 1 diabetes.
Many people with uncomplicated type 2 diabetes often
have problems with obesity.
Other signs and symptoms of hyperglycemia include
recurrent blurred vision, fatigue, paresthesias, and
skin infections. In type 2 diabetes, these often are the
symptoms that prompt a person to seek medical treat-
ment. Blurred vision develops as the lens and retina are
exposed to hyperosmolar fluids. Lowered plasma volume
produces weakness and fatigue. Paresthesias reflect a
temporary dysfunction of the peripheral sensory nerves.
Chronic skin infections can occur and are more com-
mon in people with type 2 diabetes. Hyperglycemia and
glycosuria favor the growth of yeast organisms. Pruritus
and vulvovaginitis due to
Candida
infections are com-
mon initial complaints in women with diabetes. Balanitis
secondary to
Candida
infections can occur in men.
DiagnosticTests
The diagnosis of diabetes mellitus is confirmed through
the use of laboratory tests that measure blood glucose
levels. Testing for diabetes should be considered in all
individuals 45 years of age and older. Diabetes screen-
ing should be considered at a younger age in people who
are obese, have a first-degree relative with diabetes, are
members of a high-risk group, have delivered an infant
weighing more than 9 pounds or been diagnosed with
GDM, have hypertension or hyperlipidemia, or have
met the criteria (IFG, IGT, elevated A1C) for increased
risk of diabetes on previous testing.
28
BloodTests
Blood glucose measurements are used in both the
diagnosis and management of diabetes. Diagnostic
tests include the FPG, casual plasma glucose, the glu-
cose tolerance test, and glycosylated hemoglobin (i.e.,
A1C).
10,11,28
Laboratory and capillary or finger-stick glu-
cose tests are used for glucose management in people
with diagnosed diabetes.
Fasting Plasma Glucose.
The FPG represents plasma
glucose levels after food has been withheld for at least 8
hours. Advantages of the FPG are convenience, patient
acceptability, and cost. An FPG level below 100 mg/dL
(5.6 mmol/L) is considered normal (see Table 33-3).
Casual Blood Glucose Test.
A casual (or random)
plasma glucose is one that is done without regard to
the time of the last meal. A casual plasma glucose con-
centration that is unequivocally elevated (
≥
200 mg/dL
[11.1 mmol/L]) in the presence of classic symptoms
of diabetes such as polydipsia, polyphagia, polyuria,
and blurred vision is diagnostic of diabetes mellitus
at any age.
Oral Glucose Tolerance Test.
The OGTT is an impor-
tant screening test for diabetes. The test measures the
body’s ability to store glucose by removing it from the
blood. In men and women, the test measures the plasma
glucose response to 75 g of concentrated glucose solu-
tion at selected intervals, usually 1 and 2 hours. In peo-
ple with normal glucose tolerance, blood glucose levels
return to normal within 2 to 3 hours after ingestion of
a glucose load. Because people with diabetes lack the
ability to respond to an increase in blood glucose by
