Insulin Treatment for Diabetes

Question 1

What is the normal pattern of insulin secretion that occurs in the absence of diabetes?

Answer 1

The pancreas secretes approximately 30 units of insulin per day in adults.

Basal secretion of insulin occurs without exogenous stimuli to maintain a certain concentration of insulin at all times, even while fasting. Stimulated insulin secretion occurs in response to exogenous stimuli. A plasma glucose of greater than 100 mg/dL is the most potent stimulus for insulin release.

The initial release of insulin in response to ingestion of food is termed “first-phase insulin secretion”. If glucose concentrations remain high, insulin release drops off but begins to rise again to a steady level termed “second-phase insulin secretion”. This occurs approximately 8-10 minutes after food is ingested: peripheral insulin concentration increases and peaks 30-45 minutes after starting a meal. The postprandial glucose concentration falls rapidly in response to insulin, reaching baseline levels 90-120 minutes after eating.

Physiologic insulin secretion consists of a constant basal level of insulin secretion and prandial secretion associated with ingestion of food.

Question 2

Basal bolus therapy

Answer 2

Used even when a patient is fasting.

Glargine (1ce/day), Detemir (1ce/day), and NPH insulin (2ce/day)

Basal insulin suppresses hepatic glucose output and lowers overall glucose levels throughout the day.

Patients with type 1 diabetes will develop diabetic ketoacidosis if they do not inject their basal insulin doses, while patients with type 2 diabetes will develop severe hyperglycemia but usually have enough endogenous insulin secretion to prevent ketoacidosis.

Starting doses of basal insulin can be estimated using a weight-based method (0.2 units/kg/day) but this is titrated according to individual needs and circumstances. Patients with type 2 diabetes may use up to 0.5 units/kg/day or more of basal insulin.

Typically have basal does given once/day and then pradial doses given before meals.

Question 3

Which insulins are long acting?

Answer 3

Galrgine
Detemir

1-1.5 hr onset of action
Duration of action: 24 hr

Used for basal therapy (once/day)

Can’t be mixed in same bolus as other insulins

Question 4

Which insulin is intermediate-acting?

Answer 4

NPH insulin

1-3 hr onset of action
12-16hr duration

Used for basal therapy (twice/day)

Question 5

Which insulin is short-acting?

Answer 5

Regular insulin (Humulin R, Novolin R)

30-60 min onset of action
6-8 hr duration

Used to treat diabetic ketoacidosis, hyperosmolar hyperglycemic state, and other instances of inpatient hyperglycemia

Question 6

Which insulins are rapid-acting?

Answer 6

Humalog (Lispro), Novolog (Aspart), and Glulisine (Apidra); inhaled insulin (Afrezza)

5-15 min onset of action
2hr duration

Used for prandial therapy (right before a meal)

Used effectively in continuous subcutaneous insulin infusion (insulin pump) therapy

Question 7

Prandial insulin

Answer 7

Used to metabolize nutrients in a meal or snack, and cover the postprandial rise in glucose.

The rapid-acting insulins Humalog, Novolog, and Apidra can be used for this purpose, as can inhaled insulin.

Question 8

Correctional doses of insulin

Answer 8

Used to “correct” a high blood glucose level.

The rapid-acting insulins Humalog, Novolog Apidra, and now inhaled insulin are used for this.

Question 9

Give an example of physiologic insulin dosing for type 1 diabetes

Answer 9

Glargine injected once daily (at bedtime or before breakfast) provides basal coverage for ~24 hours. “Meal boluses” consisting of set doses of rapid-acting insulin or doses calculated using carbohydrate content of the meal are administered just before each meal. Additional insulin is often added to correct high pre-meal blood glucose values using a “correction factor” or “sensitivity factor”.

5 units of rapid-acting insulin right before each meal

15 units of long-acting insulin given before bed or first thing in the morning

Question 10

Describe 2 situations in which insulin therapy is used in type 2 diabetes

Answer 10

If lifestyle modifications and non-­‐insulin combinations
don’t achieve target A1c

If come to medical attention experiencing marked weight loss with fasting blood glucoses >250 mg/dL, random glucoses of >300 mg/dL, and/or hemoglobin A1c of >10%. In this case, insulin therapy is instituted immediately because of these signs of severe insulin deficiency. Insulin therapy is continued for at least 1-2 months, and if the patient’s dose requirement decreases significantly, insulin therapy may be tapered off as other glucose-lowering therapies are added on.

Another situation necessitating the use of insulin therapy in type 2 diabetes is hospital admission for hyperglycemic hyperosmolar state or diabetic ketoacidosis. These patients are immediately placed on intravenous insulin infusions, and discharged on subcutaneous insulin regimens. After a few months of outpatient follow-up, it may be appropriate to consider tapering the insulin doses and switching to other therapies, but this cannot be determined in the acute setting.

Question 11

Basic principles of inpatient management of diabetes

Answer 11

Hyperglycemia in hospitalized patients can occur in diagnosed or undiagnosed diabetes, as a consequence of the physiologic stress of illness or surgery, and as a result of medications, or enteral or parenteral nutrition.

Inpatient hyperglycemia is associated with significant adverse outcomes.

Benefit of controlling hyperglycemia in the intensive care unit setting and also in less acutely-ill hospitalized patients on outcomes such length of stay, infection incidence, and in some studies, ICU and in-hospital mortality.

Insulin is best treatment in hyperglycemia in inpatient setting