Advanced Clinical Use of Sulfonylureas: Contraindication Analysis and Guide to Avoiding Pitfalls in Handling Drug Failures

Which diabetic patients are suitable for or not suitable for sulfonylurea hypoglycemic drugs?

(1) Sulfonylurea hypoglycemic drugs are suitable for the following diabetic patients:

① Patients whose blood sugar is still poorly controlled after diet and exercise.

② Type 2 diabetic patients with some insulin secretion function.

③ Patients with normal or slightly underweight. Because sulfonylureas can increase insulin secretion and cause weight gain, they are not the first-line drugs for obese patients.

④ Patients with good pancreatic beta-cell reserve function and no hyperglycemia. Type 2 diabetic patients only need 40U of insulin per day. Less than 20U/day is more effective. If the patient does not wish to continue using insulin, sulfonylureas can be tried as a substitute, and the dosage must be determined according to the condition.

⑤ Non-obese type 2 diabetic patients whose fasting and 2-hour postprandial blood glucose and glycated hemoglobin levels have not yet reached the target after basic treatment such as diet and exercise.

⑥ Type 2 diabetic patients with fasting blood glucose ≥11.1mmol/L, no obvious liver or kidney dysfunction, and normal peripheral blood count. (2) Sulfonylurea hypoglycemic drugs are not suitable for the following diabetic patients:

① Type 1 diabetes patients whose pancreatic beta cell function has been lost and sulfonylureas are ineffective.

② Type 2 diabetes patients whose beta cell function has failed.

③ Type 2 diabetes patients complicated by acute severe metabolic disorders (such as ketoacidosis or hyperosmolar coma).
④ Type 2 diabetes patients with stress, such as those undergoing severe infection, acute myocardial infarction, severe trauma, or surgery, should discontinue sulfonylureas and temporarily switch to insulin.

⑤ Patients with severe cardiac, hepatic, cerebral, renal, or ocular complications.

⑥ Diabetic patients with pregnancy or those who are pregnant or breastfeeding.

⑦ Children and the elderly should use sulfonylureas with caution.

⑧ Patients allergic to sulfonylureas or experiencing severe adverse reactions.

How to correctly take sulfonylurea hypoglycemic drugs?

① If a patient has never taken sulfonylureas before and no significant hypoglycemic effect is observed after one month of treatment with adequate doses, this indicates primary failure of the sulfonylureas, and insulin should be used immediately. ② If fasting blood glucose remains above 7.8 mmol/L after more than one year of long-term medication, near the maximum daily dose, and exercise and dietary therapy are also being implemented, it may indicate secondary drug failure, and the medication should be changed promptly.

③ In patients with severe acute infections, ketoacidosis, major surgery, trauma, or burns, insulin should be used instead of sulfonylureas or other types of oral hypoglycemic agents.

④ Pregnant women with diabetes should not take sulfonylureas or other types of oral hypoglycemic agents during pregnancy; insulin injection should be used instead.

⑤ Adverse reactions such as abdominal discomfort, upper abdominal burning sensation, loss of appetite, diarrhea, skin erythema, leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia, and cholestasis usually occur 6-8 weeks after medication and are generally dose-related. In such cases, the dose should be reduced, or other hypoglycemic agents should be used, or insulin should be used.

⑥ Alcohol should not be consumed while taking this medication, as it can cause hypoglycemia, abdominal pain, nausea, vomiting, headache, facial flushing, and other adverse reactions. ⑦ Concomitant use with beta-blockers may increase the risk of hypoglycemia, and this symptom may be masked by the latter. Concomitant use with chloramphenicol, phenylbutazone, salicylates, probenecid, and sulfonamides may increase the hypoglycemic effect; the dosage of sulfonylureas should be appropriately reduced. Concomitant use with corticosteroids, phenytoin sodium, thiazide diuretics, and thyroxine may lead to hyperglycemia; in this case, the dosage of sulfonylureas should be appropriately increased.

How to manage sulfonylurea failure? Sulfonylurea failure can be primary or secondary.

① Primary failure: This refers to the failure to see a significant hypoglycemic effect after one month of treatment with the maximum dose of sulfonylureas under strict dietary control. The incidence is approximately 10%. In this case, biguanides can be added. If still ineffective, insulin therapy is necessary.

② Secondary failure: This refers to the initial effectiveness of sulfonylureas after one month or longer of treatment, followed by a decrease in efficacy, and eventually, ineffectiveness. Management of secondary failure:

a. Add insulin therapy. This can be done by adding intermediate-acting insulin to breakfast and dinner, or regular insulin before meals, or intermediate-acting insulin at bedtime (9 PM);

b. Add metformin 0.25g, three times daily;

c. Add an alpha-glucosidase inhibitor, such as acarbose 50-100mg, three times daily, taken with meals;

d. Switch to insulin therapy (fiber optic pancreatic function testing);

e. Eliminate factors that trigger secondary failure, such as controlling diet and increasing exercise.

Why should sulfonylurea hypoglycemic drugs be taken before meals? Sulfonylurea hypoglycemic drugs should be taken 20-30 minutes before meals; otherwise, they are less likely to effectively control blood sugar and may cause hypoglycemia. Most sulfonylurea hypoglycemic drugs take effect about half an hour after administration, and their effect is strongest 2-3 hours after administration. Therefore, taking the medication 20-30 minutes before a meal ensures that the medication begins to take effect around the time of the meal. As food is digested and absorbed, the medication's effect intensifies, reaching its peak about two hours after the meal, which is beneficial for controlling postprandial blood sugar. If sulfonylurea medications are taken some time after a meal, the medication may not have taken effect or reached its peak effect by the time blood sugar rises after the meal, thus failing to lower blood sugar. Conversely, by the time the medication takes effect or reaches its peak effect, food absorption has already occurred for a considerable time, or it may be close to the time before the next meal, and blood sugar levels may have already decreased. In such cases, hypoglycemia may occur under the influence of the medication.