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Treatment of Type I Diabetes : Insulin

October 11, 2019

In this video, we will learn about insulin preparations, their pharmacology and treatment of type I diabetes. So, let’s begin with insulin preparations. We have rapid acting insulin such as insulin lispro, insulin aspart and insulin glulisine. We can remember them as “Rapid acting insulin do not LAG” They start showing their effect in 5 to 15 minutes. Show their peak activity in 1 hour and work for around 3 to 5 hours. Now we have short acting regular insulin or soluble crystalline zinc insulin. These regular insulin molecules self-aggregate to form dimers that stabilize around zinc ion to create insulin hexamers. After subcutaneous injection, these insulin hexamers are diluted by the interstitial fluid and the hexamers break down into dimers and finally monomers. So, this results in slow onset of action within 30 minutes which peaks between 2 and 3 hours after subcutaneous injection and generally lasts for 5 to 8 hours. Due to their slow onset, they should be given 30 to 45 minutes before meal to avoid mismatching. This mismatching means an early postprandial hyperglycemia due to incomplete fulfillment of insulin need and late postprandial hypoglycemia due to longer availability of insulin. Next is, intermediate acting isophane insulin or NPH, Neutral Protamine Hagedorn insulin. Hagedorn under the name of scientist. Protamine is because Protamine is combined with insulin so that both of them are present in complex form Neutral because the pH is neutral. After subcutaneous injection, proteolytic tissue enzymes degrade the protamine to permit absorption of insulin. This has an onset of approximately 2 to 5 hours and duration of about 12 hours. Next is long acting preparations such as Insulin glargine and insulin detemir. These long acting preparations are soluble in acidic solution but precipitate in more neutral body pH after subcutaneous injection. Insulin molecules diffuse slowly from crystalline depot and provide low continuous level of circulating insulin. They show their action in 1 to 2 hours and act for around 24 hours. These preparations have no peak activity so have less chances of occuring severe hypoglycemia. Now let’s look at the treatment of type I diabetes. In type I diabetes, our body cannot produce insulin. So, exogeneous insulin therapy is a must. The treatment includes a famous regimen Basal Bolus regimen which includes 3 to 4 daily injections of insulin. One long acting insulin once daily before breakfast or bed for the basal coverage and 2 to 3 meal time injections of Rapid acting insulin to control postprandial hyperglycemia. This regimen has an advantage of reducing the progression of disease and occurrence of complications. But is expensive and is best avoided in young children due to the risk of hypoglycemic brain damage and in elderly (and renal patients) who are more prone to hypoglycemia and its consequences. Another regimen is split-mixed regimen or conventional regimen which involves mixture of regular with isophane insulin in the ratio 30:70 or 50:50 split in two doses and injected subcutaneously before breakfast and dinner. This regimen has a disadvantage of inadequate coverage of post lunch hyperglycemia and late postprandial hypoglycemia can occur. It has less control of diabetes and its complications.

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