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What would be the most likely cause for a patient with
Type 2 diabetes to have higher fasting glucose levels then their postprandial
glucose levels?
1. Timing of medication
2. Amount of medication
3. Type of medication
4. Over production of liver glucagon
Patients with type 2 diabetes can usually be divided into 3 patterns
of glucose during the day.
Probably the majority (but not by much) have fairly similar premeal
glucoses throughout the day. The second most common pattern is characterized
by glucose being highest in the morning in the fasting state. Remember,
fasting glucose is determined by the insulin sensitivity of the liver
and insulin secretion. Generally, insulin secretion is fairly intact
in early diabetes, but often the insulin-secreting cells do not respond
to glucose. These patients often will respond to feeding a mixed meal
(carbohydrate, protein, and fat) and almost always respond to metformin
provided at bedtime. In patients with this pattern of fasting hyperglycemia,
a fairly long-acting sulfonylurea such as glimepiride (Amaryl; Aventis
Pharmaceuticals Inc., Kansas City, Missouri) given with supper or at
bedtime, even in modest doses (0.5-2 mg) can have a dramatic effect
on fasting glucose. By providing this agent in the evening, higher levels
of sulfonylurea are present during the night to maintain insulin secretion
and these levels will start to wane during the day when the patient
is active and may be more prone to hypoglycemia.
There are some patients whose blood glucose rises throughout the day
as they eat. They more often have a substantial insulin secretory defect
and need treatment with sulfonylureas or insulin; some may be profoundly
insulin resistant and will respond to a glitazone. Remember, clearing
glucose from the circulation after a meal requires insulin secretion
and insulin action in muscle and fat.
The most common cause of hypoglycemia in the postprandial state would
be a postprandially active drug, generally a rapid-acting insulin analogue.
When this occurs frequently in patients, we often have them switch to
taking their lispro (Humalog; Eli Lilly and Company, Indianapolis, Indiana)
or aspart (NovoLog; Novo Nordisk Pharmaceuticals Inc., Princeton, New
Jersey) after meals.
Medscape Diabetes & Endocrinology 5(1)
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