CHAPTER 12 Common Endocrinologic Disorders
I. Diabetes Mellitus
A. Classification
1. Type 1 diabetes is a failure of the pancreas to make enough insulin for the body to function. It was previously called insulin-dependent diabetes or juvenile-onset diabetes. It occurs more often in younger patients than older patients. Type 1 diabetes requires insulin therapy.
2. Type 2 diabetes refers to decreased insulin production from the pancreas, decreased sensitivity of cells to insulin, and decreased ability to get glucose into cells. It was previously called non–insulin dependent diabetes and adult-onset diabetes. It occurs more often in older patients than younger patients, although the incidence of type 2 diabetes is increasing in children in the United States. Patients may start with diet and exercise therapy. Most patients start with oral medications but may progress to requiring insulin therapy.
3. Gestational diabetes is diabetes that occurs during pregnancy. It does not mean the patient will have diabetes for the rest of her life, but she will have increased risk of developing type 2 diabetes. Patients typically use insulin therapy due to risk to the fetus when using oral antidiabetic medications. Gestational diabetes is usually detected through administration of an oral glucose tolerance test (OGTT) during pregnancy.
D. Goals of therapy
| Target Area | Treatment Goals (for the patient with diabetes) |
|---|---|
| Preprandial plasma glucose (fasting) | 90–130 mg/dL |
| Postprandial plasma glucose (after meals) | <180 mg/dL |
| Glycosylated hemoglobin (HbA1c) | <7% |
| Blood pressure | <130/80 mmHg |
| Lipid levels |
Based on the American Diabetes Association guidelines. Individual treatment goals may vary slightly from these guidelines based on personal medical history.
F. Insulin
1. Background
a) Insulin is produced in the beta cells of the pancreas. It is released at a basal rate of 0.5 to 1 U/h. Insulin response is increased in response to food.
2. Types of insulin
b) Intermediate-acting
(2) Dosed twice daily for optimal control; may also be dosed once daily at bedtime for patients with type 2 diabetes who also take oral medications to suppress overnight hepatic gluconeogenesis
3. Cautions
e) Caution is warranted when switching from animal (either pork or bovine) to purified porcine insulin or biosynthetic human insulin due to increased potentcy or bioavailability and increased risk of hypoglycemia.
6. Remarks regarding insulin
8. Adjusting insulin dose
d) Long-acting insulin should be adjusted based on fasting glucose
Starting Insulin: Staged Diabetes Management Guideline (SDM)
From Staged Diabetes Management, ed 4 © 2005, International Diabetes Center at Park Nicollet, Minneapolis, MN. All rights reserved. Reprinted with permission (+1)800-637-2675; and Pearson J, Powers M: Systematically Initiating Insulin: The Staged Diabetes Management Approach, The Diabetes Educator 32(Suppl)(1):23s–25s, 2006.
Guideline for starting and titrating background insulin: Background insulin + oral agent(s) insulin glargine or insulin detemir
| <70 mg/dL | Decrease 1–2 U |
| 140–250 mg/dL | Increase 2–4 U |
| >250 mg/dL | Increase 4–8 U |
0.1 U/kg body weight if A1c levels are <9% (long acting insulin)
0.2 U/kg body weight if A1c levels are ≥9%
Adjustments are made weekly based on fasting blood glucose.
Guideline for starting and titrating premixed insulin: Premixed insulin Aspart 70/30 or Lispro premix 75/25
Blood Glucose Adjust Insulin*
Prebreakfast
| <70 mg/dL | Decrease pm 1–2 U |
| 140–250 mg/dL | Increase pm 1–2 U |
| >250 mg/dL | Increase pm 2–4 U |
Presupper
| <70 mg/dL | Decrease am 1–2 U |
| 140–250 mg/dL | Increase am 1–2 U |
| >250 mg/dL | Increase am 2–4 U |
0.1 U/kg in morning and evening if A1c <9%
0.2 U/kg in morning and evening if A1c ≥9%
Guidelines for starting and titrating background/mealtime insulin: Long-acting insulin (insulin glargine or insulin detemir) + rapid-acting insulin with meals
| Blood Glucose | Adjust Insulin† |
| Prebreakfast | Long-acting (detemir or glargine) |
| Prelunch am | Rapid acting |
| Presupper lunch | Rapid acting |
| Prebedtime supper | Rapid acting |
| Start | If A1c <9%: |
| If A1c ≥9%: | |
| Total units | 0.2–0.4 U/kg |
| Adjust | Minimum weekly |
G. Synthetic amylin analog, pramlintide acetate (Symlin)
1. Mechanism of action: synthetic analog of human amylin
a) Amylin, like insulin, is located in pancreatic beta cells. It is secreted with insulin in response to food intake.
3. Usual adult dosage
a) Type 1 diabetes: initially, 15 mcg SC before meals; may titrate up at 15 mcg increments (without nausea for 3 days); maintenance: 30–60 mcg SC before meals
H. Incretin mimetic agent, exenatide (Byetta)
1. Mechanism of action
a) Stimulates the body’s ability to produce insulin in response to elevated concentrations of blood glucose
I. Oral agents for diabetes
1. Sulfonylureas
b) First generation versus second generation-
(1) Fewer adverse effects with second generation agents (e.g., glyburide, glipizide), although patient is still at risk for hypoglycemia
c) Indications: management of type 2 diabetes as monotherapy; also combined with other antidiabetic medications if needed (e.g., metformin, insulin)
d) Usual adult dosage
| Generic (Brand) | Adult Daily Dose Range | |
|---|---|---|
| First generation | Acetohexamide (Dymelor) | 250–1500 mg |
| Tolbutamide (Orinase) | 500–3000 mg | |
| Tolazamide (Tolinase) | 100–1000 mg | |
| Chlorpropamide (Diabinese) | 100–500 mg | |
| Second generation | Glipizide: | |
| Glyburide: | ||
| Glimepiride (Amaryl) | 1–4 mg |
