00:00
In these lectures, we're going to talk about diabetes mellitus. Diabetes mellitus can be defined
as a chronic metabolic disease characterized by elevated plasma glucose. This is usually due to
insulin deficiency in the case of type 1 diabetes. Type 1 diabetes can be immune mediated
due to beta cell destruction or idiopathic, which is non-immune mediated. This particular type is
very rare. Acquired diabetes is diffuse damage of the beta cells with subsequent insulin deficiency
and this can occur from infections or drugs that affect the pancreas. Impaired action of insulin
secondary to insulin resistance is the hall mark of type 2 diabetes, probably the most common
form of diabetes the we encounter in medical practice. One fails to get the combination of these 2
abnormalities. Prediabetes is defined as elevated plasma glucose levels below the diagnostic criteria
for diabetes but above of the normal range. Gestational diabetes or pregnancy-induced diabetes is
any degree of glucose intolerance with onset or first recognition during pregnancy. The definition
applies where the insulin or only diet modification is used for treatment and whether or not the
condition persists after pregnancy. Elevated plasma glucose can be defined as plasma glucose
level that occurs between the range of 100 and 125 mg/dL. Also, on a glucose tolerance test,
a range of plasma glucose between 140 and 199 mg/dL. This is usually 2 hours after a 75 gram oral
glucose load. And then finally a glycosylated hemoglobin level or hemoglobin A1c of 5.7-6.4%.
02:05
Criteria for diagnosing diabetes are numerous and this particular series of slides will take you
through differentiating the normal range, prediabetes, and overt diabetes mellitus. A random plasma
glucose in the setting of classic hypoglycemic symptoms such as polyuria, polydipsia, polyphagia
plus a plasma glucose level that exceeds or is equal to 200 mg/dL will give you the diagnosis
of diabetes. Fasting plasma glucose after an 8-hour fast within the normal range should be less than
100 mg/dL. Prediabetes is defined as a fasting plasma glucose between 100 and 125 mg/dL and overt
diabetes occurs when the fasting plasma glucose is greater than or equal to 126 mg/dL. Plasma
glucose during a 2-hour 75 gram oral glucose tolerance test under normal circumstances should be
less than 140 mg/dL. In prediabetes, this will range between 140 and 199 and in overt diabetes
greater than 200 mg/dL. Hemoglobin A1c of less than 5.7 is normal, between 5.7 and 6.4 indicates
prediabetes, and overt diabetes is diagnosed when the hemoglobin A1c exceeds 6.5%. I referred
early in the slide to classic hyperglycemic symptoms. There is a generally accepted triad, although
they don't necessarily always occur in patients with diabetes, but more often than not excessive
urination or polyuria, excessive hunger or polyphagia, and excessive thirst or polydipsia are
hallmarks of elevated serum glucose. In the absence of hypoglycemic symptoms, an abnormal fasting
plasma glucose, an abnormal oral glucose tolerance test, or hemoglobin A1c should be confirmed by
repeated testing. Let's say a few words about the metabolic syndrome. This is a group of risk
factors that increase the probability of developing type 2 diabetes mellitus and cardiovascular
disease. This in turn can result in impaired glucose metabolism, central body obesity, hypertension,
and hyperlipidemia. There is also an increased relative risk of developing cardiovascular disease
and an increased risk of developing diabetes. In fact, the risk for cardiovascular disease is
2 times normal and the risk for developing overt diabetes is 5 times normal.