Reactions to Insulin

| Home | | Pharmacology |

Chapter: Essential pharmacology : Insulin, Oral Hypoglycaemic Drugs and Glucagon

Hypoglycaemia : This is the most frequent and potentially the most serious reaction. It is commonly seen in patients of ‘labile’ diabetes in whom insulin requirement fluctuates unpredictably.


REACTIONS TO INSULIN

 

Hypoglycaemia

 

This is the most frequent and potentially the most serious reaction. It is commonly seen in patients of ‘labile’ diabetes in whom insulin requirement fluctuates unpredictably. Hypoglycaemia can occur in any diabetic following inadvertent injection of large doses, by missing a meal or by performing vigorous exercise. The symptoms can be divided into those due to counterregulatory sympathetic stimulation— sweating, anxiety, palpitation, tremor; and those due to deprivation of the brain of its essential nutrient glucose (neuroglucopenic symptoms) — dizziness, headache, behavioural changes, visual disturbances, hunger, fatigue, weakness, muscular incoordination and sometimes fall in BP. Generally, the reflex sympathetic symptoms occur before the neuroglucopenic, but the warning symptoms of hypoglycaemia differ from patient to patient and also depend on the rate of fall in blood glucose level. After longterm treatment about 30% patients lose adrenergic symptoms. Diabetic neuropathy can abolish the autonomic symptoms. Hypoglycaemic unawareness tends to develop in patients who experience frequent episodes of hypoglycaemia.

 

Finally, when blood glucose falls further (to < 40 mg/dl) mental confusion, abnormal behaviour, seizures and coma occur. Irreversible neurological deficits are the sequelae of prolonged hypoglycaemia.

 

Treatment Glucose must be given orally or i.v. (for severe cases)—reverses the symptoms rapidly. Glucagon 0.5–1 mg i.v. or Adr 0.2 mg s.c. (less desirable) may be given as an expedient measure in patients who are not able to take sugar orally and injectable glucose is not available.

 

Local Reactions

 

Swelling, erythema and stinging sometimes occur especially in the beginning. Lipodystrophy occurs at injection sites after long usage. This is not seen with newer preparations—which may even facilitate reversal of lipoatrophy when injected at the same sites.

 

Allergy

 

This is infrequent; is due to contaminating proteins; very rare with human/highly purified insulins.

 

Urticaria, angioedema and anaphylaxis are the manifestations.

 

Edema

 

Some patients develop shortlived dependent edema (due to Na+ retention) when insulin therapy is started.

 

Drug Interactions

 

1) β adrenergic blockers prolong hypoglycaemia by inhibiting compensatory mechanisms operating through β2 receptors (β1 selective agents are less liable). Warning signs of hypoglycaemia like palpitation, tremor and anxiety are masked. Rise in BP can occur due to unopposed α action of released Adr.

 

2)    Thiazides, furosemide, corticosteroids, oral contraceptives, salbutamol, nifedipine tend to raise blood sugar and reduce effectiveness of insulin.

 

3)    Acute ingestion of alcohol can precipitate hypoglycaemia by depleting hepatic glycogen.

 

4)    Salicylates, lithium and theophylline may also accentuate hypoglycaemia by enhancing insulin secretion and peripheral glucose utilization.

 

Contact Us, Privacy Policy, Terms and Compliant, DMCA Policy and Compliant

TH 2019 - 2022 pharmacy180.com; Developed by Therithal info.