3.3 Insulin and other injectable agents

Indications of insulin:

• Type 1 DM
• Severe acute complication/illness e.g. MI, acute infection
• Uncompensated chronic complication or illness
• Pregnancy and lactation
• At least 3-5 months prior to planned conception
• Major surgery
• OAD failure
• Poor glycemic status
  • HbA1c >10%
  • FBS >14 mmol/L, RPG >18 mmol/L (with or without symptom)
  • HbA1c >7% in spite of 50% of maximum dose of SU and maximum tolerable dose of sensitizer
  • Symptomatic hyperglycemia

How to start and adjust insulin^3,4:

1. Start with 0.2-0.5 unit/kg/day.
2. Premixed or coformulation: Start with two third of the total calculated dose in the morning and one-third at the evening (To start at a low dose with gradual up or down titration).
3. Split-mixed: Two third of the total dose will be intermediate acting and one third short acting. Among this two third dose in morning and one third dose at evening.
4. Basal insulin of 10 unit/day or 0.1-0.2 unit/kg/day. Fixing the fasting first. If postprandial still not within target, add bolus insulin 4 unit/day or 10% of basal dose.
5. Increase dose by 2-4 units every 3 days to reach the target.
6. Decrease dose by 2-4 units if blood sugar is below the target.

Continuous subcutaneous insulin infusion (CSII) pump:

Continuous subcutaneous insulin infusion is a mode of delivering intensive insulin therapy, which usually leads to improved glycemic control and reduced glycemic fluctuation. It is a battery operated, portable, programmable pump to continuously deliver rapid-acting insulin via an infusion set inserted subcutaneously. Insulin pump is an alternative to treatment with multiple daily injection. Children with T1DM having multiple episodes of hypoglycemia or uncontrolled diabetes requiring multiple daily injection and T2 DM requiring high dose of insulin (>10 unit/kg) and not achieving glycemic target are candidates for CSII.

Insulin injection technique¹:

• Injections are given into the deep subcutaneous tissue at 45-90° angle by two-finger pinch of skin. The pinch is recommended to ensure a strict subcutaneous injection; avoiding intramuscular injection. Injections can be given perpendicularly without lifting a skin fold when needles are smaller and there is enough subcutaneous fat. Needles should be inserted full, otherwise there is a risk of intradermal injections. A wait of 15 seconds after pushing the plunger helps to ensure complete expulsion of insulin through the needle, especially in pens. Cleaning or disinfection of skin is advisable, but may not be necessary unless hygiene is a real problem.
  
  
• Vials (also the pen devices) of cloudy insulin must always be gently rolled (not shaken) 10- 20 times, to mix the insulin suspension. When two insulins are drawn (e.g. regular insulin is mixed with NPH), the regular insulin is to be drawn before the intermediate acting one. The mixture must be administered immediately.
  
  
• Abdomen is the preferred site when faster and uniform absorption is required; it is less affected by muscle activity or exercise. Front and lateral aspects of thigh is the preferred site for slower absorption of longer acting insulin. Lateral aspect of upper arm is another site, but assistance is required for injection. The lateral upper quadrant of the buttocks is used less often. Rotation of injection sites are important within the same area of injection.

Storage of insulin¹:

Insulin must never be frozen. Direct sunlight or warming (e.g. in hot climates) damages insulin. Insulin should not be used if there is change in appearance (clumping, frosting, precipitation or discoloration). Unused insulin should be stored in a refrigerator (4-8° C) to retain its potency up to expiry date. When in use, the insulin can be kept in room temperature (if not too hot) without much loss of efficacy. But it retains its potency much better if kept in refrigerator. In hot climates where refrigeration is not available, cooling jars, earthenware pitcher or cool wet cloth around the insulin container will help to preserve activity.