What is the role of insulin in managing diabetes?

Insulin's Role in Diabetes Management

Insulin is essential for managing diabetes, serving as the primary treatment for type 1 diabetes and an important therapy for many patients with type 2 diabetes when blood glucose control cannot be achieved with other medications. 1

Physiological Role of Insulin

• Insulin is necessary for normal carbohydrate, protein, and fat metabolism in the body 1
• It primarily regulates glucose metabolism by stimulating peripheral glucose uptake, especially by skeletal muscle and fat, and by inhibiting hepatic glucose production 2
• Insulin inhibits lipolysis and proteolysis while enhancing protein synthesis 2

Types of Diabetes and Insulin Requirements

Type 1 Diabetes

• People with type 1 diabetes do not produce enough insulin to sustain life and therefore depend on exogenous insulin for survival 1
• Multiple daily injections are typically required at diagnosis, usually involving short-acting or rapid-acting insulin before meals with one or more daily injections of intermediate or long-acting insulin 3

Type 2 Diabetes

• Individuals with type 2 diabetes are not initially dependent on exogenous insulin for survival 1
• However, over time, many will show decreased insulin production, requiring supplemental insulin for adequate blood glucose control, especially during times of stress or illness 1
• Insulin is indicated in type 2 diabetes when HbA1c is ≥7.5% despite optimal use of other antihyperglycemic agents, and is essential when HbA1c is ≥10% 3

Types of Insulin

• Insulin is available in rapid-, short-, intermediate-, and long-acting formulations that may be injected separately or mixed in the same syringe 1
• Basal insulins (NPH, glargine, detemir, degludec) provide relatively constant insulin levels to control blood glucose between meals and overnight 4
• Rapid-acting insulin analogs (insulin lispro and insulin aspart) are available for mealtime coverage 1
• Insulin analogs are developed by modifying the amino acid sequence of the insulin molecule 1

Insulin Administration

Storage and Handling

• Vials of insulin not in use should be refrigerated 1
• Extreme temperatures (<36 or >86°F, <2 or >30°C) and excess agitation should be avoided to prevent loss of potency 1
• Insulin in use may be kept at room temperature to limit local irritation at the injection site 1
• Patients should always have a spare bottle of each type of insulin used 1

Administration Techniques

• The shortest needles (4-mm pen and 6-mm syringe needles) are safe, effective, and less painful 3
• Count to 10 after the plunger is fully depressed before removing the needle from the skin to prevent leakage 1
• Intramuscular injections should be avoided, especially with long-acting insulins, as severe hypoglycemia may result 3

Insulin Dosing and Adjustment

Initial Dosing

• Basal insulin is typically initiated at 10 units or 0.1-0.2 units/kg/day, depending on the degree of hyperglycemia 4
• Dose adjustments are made based on fasting blood glucose levels 4

Self-Monitoring and Adjustment

• Self-monitoring of blood glucose (SMBG) is extremely valuable for patients taking insulin 1
• Insulin dosage adjustments should be based on blood glucose measurements, not on food intake alone 5
• During illness, more frequent monitoring (every 2-4 hours) is recommended 5

Special Considerations

During Illness

• Insulin must be continued during illness even if the patient is unable to eat or is vomiting 1, 5
• Insulin requirements often increase during illness despite decreased food intake 5
• Oral ingestion of 150-200g of carbohydrate per day is recommended during illness to prevent starvation ketosis 5

Hypoglycemia Management

• Excess insulin is a common cause of hypoglycemia 1
• All insulin-requiring individuals should carry at least 15g of carbohydrate to treat hypoglycemic reactions 1
• Family members, roommates, and others should be instructed in glucagon use for severe hypoglycemia 1

Special Populations

• In geriatric patients, initial dosing, dosage increments, and maintenance dosage should be conservative to avoid hypoglycemia 2
• For patients with renal or hepatic impairment, frequent glucose monitoring and dosage adjustment may be necessary 2

Common Errors and Safety Considerations

• Medication errors involving insulin can occur at each step of the medication-use process: prescribing, data entry, preparation, dispensing, and administration 6
• Wrong-dose errors have been caused by abbreviations, especially "U" instead of "units" 6
• The same injection pen should never be used for multiple patients due to risk of viral contamination 6

Psychological Aspects of Insulin Therapy

• Beginning insulin therapy can involve psychological hurdles, particularly fear of pain 1
• Patients should understand that improving blood glucose control will improve overall health and well-being 1
• It's important to explain that insulin is not a punishment or failure but the best treatment available for managing blood glucose levels 1