A 2-hour OGTT greater than or equal to 200 mg/dL (fasting sample, 60-, and 120-minute samples) after a 75-g load of glucose. A 2-hour OGTT should not be performed if the first two criteria are present.
Diagnostic criterion for impaired glucose intolerance (IGT) is a fasting glucose greater than or equal to 100 mg/dL but less than 126 mg/dL (36).
A 2-hour OGTT should be performed under the following conditions: 1.
A 10-hour fast should precede morning testing.
2.
The patient should sit throughout the procedure.
Assessment of Glycemic Control 3.
No smoking is permitted during the test interval.
4.
Caffeinated beverages should not be consumed.
5.
More than 150 g of carbohydrates should be ingested for 3 days before the test.
6.
No drugs should be taken before the test.
7. The patient should not be bedridden or under stress. Patients who should be considered for diabetes testing are:
All individuals 45 years of age or older (repeat at 3-year intervals)
Persons with classic signs and symptoms of diabetes (i.e., polyuria, polydipsia, polyphagia, and weight loss)  Ethnic groups at high risk (Pacific Islanders, Native Americans, African Americans,
Hispanic Americans, and Asian Americans)  Obesity (body mass index >27 kg/m2)  History of a first-degree relative with diabetes  Women with gestational diabetes or who have delivered a baby weighing more than 9 pounds  Individuals with hypertension (blood pressure >140/90 mm Hg)  An HDL cholesterol level less than or equal to 35 mg/dL or triglyceride level greater than or equal to 250 mg/dL  Presence of impaired glucose tolerance on previous testing
The only acceptable method for assessment of glycemic control is determination of blood glucose by direct enzyme analysis, not by measurement of urine values, which do not correlate. Glucometers with memory storage made home glucose monitoring more reliable. Physician treatment guidelines are in Table 9.10 and patient guidelines in Table 9.11. In a 10 multicenters’ study, the diabetes control and complication trial (DCCT), performed under the auspices of the National Institutes of Health, showed a marked reduction (40%–50%) in complications of neuropathy, retinopathy, and nephropathy when patients with type 1 diabetes received intensive therapy (accomplished by a team approach) as compared with those who received standard therapy.
Oral Hypoglycemic Agents Oral hypoglycemic agents are recommended for many type 2 diabetic patients. The first oral hypoglycemic agents introduced were first-and second-generation sulfonylureas. Other classes of drugs that have different effects in patients with type 2 diabetes—such as biguanides, thiazolidinediones, alpha-glucosidase inhibitors, and insulin secretagogues—were introduced. The mode of action of sulfonylureas is based on two different mechanisms: (i) enhanced insulin secretion from the pancreas, and (ii) an extrapancreatic effect that is poorly understood. Endogenous insulin secretion (as measured by C-peptide) is necessary for oral hypoglycemic agents to work. If the fasting blood glucose on an adequate diabetic diet is greater than 250 mg/dL, there is little effect. Frequent evaluation to monitor control (every 3 to 4 months) is important. If glucose levels cannot be controlled with oral hypoglycemic agents (i.e., sulfonylureas) or other
Table 9.10 Physician Guidelines in the Therapy of Diabetes Mellitus