Insulin Pump

Epidemiology

Insulin Pump used by more than half of Type I Diabetics

Background

Device that delivers Insulin subcutaneously
1. Most patients use a rapid-acting Bolus Insulin (e.g. Lispro or Humalog) in Insulin reservoir
2. Device can deliver Insulin basal rates down to 0.01 units/h
Costs
1. Pumps typically cost $6000 with a monthly cost of $300 for supplies (2016)

Components

Insulin Pump
1. Insulin reservoir (disposable)
  1. Filled with U-100 (100 U/ml) Bolus Insulin (highly concentrated)
  2. Bolus Insulin used is typically Insulin Lispro (Humalog) or Insulin Aspart (Novolog)
  3. Bolus Insulin is infused at a slow basal rate plus meal time bolus doses
2. Control pad
  1. Pager-sized hand-held computer with small screen
  2. Enter Insulin Infusion maintenance rate (basal rate)
  3. Enter bolus dose directly or calculated based on carbohydrate intake
Infusion set (disposable)
1. Tubing
  1. Connects Insulin Pump to subcutaneous insertion site
  2. May be disconnected when showering, bathing, swimming
2. Cannula to insert subcutaneously
  1. Introduced in similar fashion to IV start (except subcutaneous)
  2. Needle is used to introduce the catheter subcutaneously
  3. Needle is removed after insertion and catheter is left in place
3. Variations
  1. Omnipod
    1. Wireless Insulin reservoir attached directly to body at subcutaneous insertion site
    2. No tubing is required
    3. Controlled by a wireless device
Insertion site
1. Subcutaneous cannula with adhesive to hold it in place
2. Changed every 3 days (up to 5 days)
  1. Rotate infusion sites to avoid infection, Lipodystrophy
3. In rare cases, site may become infected
Additional functions
1. Some pumps allow for Continuous Glucose Monitoring
2. Some pumps are waterproof (others must be removed for bathing or swimming)
3. Pumps function continuously (providing basal Insulin) and pausing pump (without detaching) is more complicated

Protocol
Pump Malfunction

Typically results in Hyperglycemia (not Hypoglycemia)
Examples
1. Pump failure
2. Tube disconnected
3. Infusion set leak
4. "Insulin Bad"
5. Subcutaneous insertion site problem (e.g. insertion at scarred tissue)

Protocol
Persistent Hyperglycemia

Have emergency supply of backup Insulin and syringes in case of pump failure
Attempt to use pump to deliver Insulin boluses
1. Tests if the Insulin Pump (and infusion set) is functional
Persistently high Blood Glucose values
1. Subcutaneous Insulin injections can still be given in addition to pump
Detach the pump in severe hyperglycemia Critical Illness or Diabetic Ketoacidosis
1. Manage per Insulin Drip or Hourly Subcutaneous Insulin protocols

Protocol
Hypoglycemia

See Hypoglycemia Management in Diabetes Mellitus
Immediately detach pump in severe hypoglycemic episode
Causes
1. Patient error (too high of Insulin dose selected)
2. Acute illness (e.g. Acute Kidney Injury, infection)

Procotol
Hospitalization

Consult endocrinology as needed
Detach the Insulin Pump during hospitalizations where Insulin will be managed by nursing and provider orders
However, leave Insulin Pump attached in most cases to provide Insulin basal rate
1. Risk of DKA while detached (patient has no sustained basal Insulin activity, e.g. Insulin Glargine)

Adverse Effects

Lipodistrophy
Cannula site pain

Safety

Diabetic Ketoacidosis is NOT more common with Insulin Pumps (per T1D registry)
1. Theoretic risk of unrecognized pump failure did not occur significantly in reality

Resources

American Diabetes Association
1. http://www.diabetes.org/living-with-diabetes/treatment-and-care/medication/insulin/insulin-pumps.html
Wikipedia
1. http://en.wikipedia.org/wiki/Insulin_pump

References

Claudius and Pedigo (2021) EM:Rap 21(8): 10-12
Smith (2018) Am Fam Physician 98(3): 154-62 [PubMed]