Insulin therapy (review with handout) Flashcards
How much insulin does pancreas secrete daily?
30 units
-secretion at a basal level and in response to glucose
Phases of insulin secretion
first phase: initial release in response to ingestion of food, then drops off
second phase: occurs with sustained hyperglycemia
Physiologic insulin secretion consists of a constant basal level of insulin secretion and prandial secretion associate with ingestion of food.
Who needs insulin?
ALL patients with type 1 diabetes, some pts with type 2 diabetes
Making insulin
Make by modifiying human insulin
a chain and b chain connected by disulfide bonds
lispro (proline and lysine reversed)
aspart (aspartate instead)
glulisine (most recent): lysine at B3 and glutamamte at B29
Rapid acting insulin
humalog (Lispro) novolog (Aspart) glulisine (Apidra)
Onset of action 5-15 min peak 1-1.5 hr Duration 3-5 hr SQ injection or insulin pump Given just prior to a meal Dissociates rapidly into monomers after injection
Inhaled insulin
- Afrezza
- onset of action 5 min
- peak 1 hr
- duration 2 hr
- set dose cartridges for inhalation device
- admin just prior to a meal
Short-acting: regular insulin
Humulin R
Novolin R
- Onset of action 30-60 min
- peak 2 hr
- duration 6-8 hr
- SQ injection, IV infusion
- inject 30 minutes before eating
- IV infusion can treat DKA
- knowing when to inject is difficult w/ long DOA
- risk of hypoglycemia
- used in hospitals for IV infusion (if used as IV, no difference b/t this and rapid acting insulin analogues)
Intermediate-acting: NPH (neutral protamine Hagedorn)
Humulin N; Novolin N
- Onset of action 1-3 hr
- Peak 6-8 hr
- Duration 12-16 hr
- SQ injection only (>2x/d for basal coverage)
- cloudy solution!!
- inexpensive!
- could inject in morning and have peak around lunchtime
- must be well mixed
NPH and regular insulin is cheapest regimen
Long-acting insulin
glargine (Lantus)
detemir (Levemir)– more lipophilic, binds to albumin in circulation
-onset 1-1.5 h
-no pronounced peak
-Duration 24 hr (glargine) or 12-20 hr (detemir)
-SQ injection only
-CANNOT be mixed in the same syringe with any other insulins (has acidic pH)
-can give 1x/d w/ glargine
-often 2x/d detemir
Premixed (biphasic) insulins XX (not LO)
Human insulins (%NPH/% regular) 70/30 50/50 Analog insulins Humalog 75/25 Humalog 50/50 Novolog 70/30 Used twice a day before AM and PM meals SQ only
-Mixture of intermed and short or rapid acting insulins taken to meet basal AND meal insulin needs
NPH + regular: inject 30 mins before meals: 70/30 (NPH/reg)
Insulin analog premixes: inject 15 mins QAC
-int plus humalog (75/25; 50/50)
Intermed plus novolog
70/30
Pharmacokinetics of insulin
- volume
- concentration
- body site (thigh vs. abdomen vs arm)
- presence of lipodystrophy
- intradermal vs subq vs intramuscular: if the site is warm, rubbed or exercised
How much of day is basal vs bolus/rapid acting?
50% bolus
50% basal
Basal insulin
insulin taken to suppress hepatic glucose production and to maintain normal fasting blood glucose levels
Glargine
Determir
NPH
Type 1: DKA without this.
Type 2: severe hyperglycemia
Starting dose: 0.2units/kg/d
prandial insulin
- insulin taken to cover the rise in glucose from a meal: fixed dose OR acording to carbohydrate content of meal
- Humalog OR novolog or glulisine or inhaled insulin before each meal
Carb to insulin ratio: number of grams of carbs that 1 unit of insulin is anticipated to “cover”
C:I of 15:1 or 10:1 if insulin resistant
Prandial + correctional insulin makes up “bolus” insulin. Pts on this are on basal bolus therapy
Correction dose insulin
- insulin taken to correct pre-meal hyperglycemia
- often added to meal/prandial dose
- can be taken alone (in between meals)
- caution: do not “stack’ corrections
Correction factor: 1600/total daily dose of insulin. Gives how much one unit of insulin will lower blood glucose (mg/dl)
Humalog OR novolog or glulisine or inhaled insulin
Treatment regimen for type 1
lispro/aspart/glulisine/ inhaled at each meal
glargine qHS
OR
rapid acting at each meal
Detemir at AM and PM meal
Continuous subcutaenous insulin infusion therapy
- insulin pump
- controlled, programmable
Problem: if you aren’t good with technology or don’t know how to trouble shoot (air bubbles, infusion catheter issues, kink in system); could lead to DKA
Advantages:
- elim multiple daily injection
- different basal rates (“Dawn phenomenon”; workweek/weekend)
- small increment boluses are possible
- Different bolus types (square vs dual wave)
Advantages to insulin pump therapy
Advantages:
- elim multiple daily injection
- different basal rates (“Dawn phenomenon”–marked rise in blood sugar in mornings b/t 4-8 am; workweek/weekend)
- small increment boluses are possible
- Different bolus types (square vs dual wave)
Disadvantages to insulin pump therapy
- upfront cost
- significant training
- motivation
- ability to troubleshoot
- interruption of infusion or “bad site” can lead to major problems (DKA) within 4-5 hours
What to consider when choosing regimen
- age
- duration of diabetes
- complications (hypoglycemia unawareness, retinopathy, etc)
- Patient’s motivation
- Patient’s self management skills
- Daily schedule–skipped meals? activity?
Insulin tx for type 2 diabetes
-if lifestyle modifications and non-insulin combinations don’t achieve target A1c
-OR contraindications to other meds (renal or hepatic dysfunction, CHF)
Always if:
-signs of insulin deficiency on presentation (wt loss; fasting blood glucose >250; random blood gluc >300; HbA1c >10%)
-Hospital admission for diabetic emergency:
hyperglycemic hyperosmolar state; DKA: IV insulin infusion, discharge with subq insulin regimen
Barriers to insulin therapy
Pt:
- fear of injections
- fearof hypoglycemia
- fear of gaining wt
- belief that insulin means serious DM
- belief it causes blindness
- inconvenience
- stigma
Physician:
- uncertainty about whether insulin is really necessary
- difficulty initiating and adjusting therapy: time , experience, staffing
- fear of hypoglycemia
- fear of inducing wt gain
Glucose and A1c targets
Fasting BG: 70-130
2hr post meal BG:
Type 2 DM algorithm
NPH QHS orglargine/detemir QD: 10 units or 0.2 u/kg
- check fasting bg qam
- increase dose by 2 units q3 d until
