SINGLE DOSE REGIMES :-

This is mentioned as it is frequently used, but rarely, if ever, is it possible to achieve glycemic control with this. The starting dose is usually in the range of 0.2-0.3 U/Kg per day. Most patients will require much larger doses of approximately 0.5-1.0 U/Kg per day as they have no endogenous insulin secretion, but it is advisable to start with lower doses as the patient may develop hypoglycemia and because patient may have some endogenous insulin secretion intact. The choice of insulin is usually a combination of regular insulin (approximately 30%) with an intermediate acting insulin (NPH or lente) given about 30-45 min prior to breakfast (Fig 1A). The insulin dosages are gradually adjusted as per self-monitoring of blood glucose (before breakfast, late afternoon [post lunch] and pre dinner). This regime may be of some use in those patients who have some endogenous insulin secretion, or those that are in their honeymoon phase, but as mentioned, more often than not the patient has to be shifted to twice daily or multiple daily injection regimes to achieve glycemic control (9,10)

TWICE DAILY REGIMES :-

Patients on single daily injection regimen often have a high fasting glucose but low or normal glucose levels in the afternoon and evening. This is because both NPH and Lente insulin have duration of action lasting between 8-18 hours. In such a situation a second injection of a intermediate acting insulin can either be given singly at bedtime or in combination with a regular insulin before dinner (Split mix regime). Many diabetologists initiate insulin therapy with a minimum of two injections (Fig 1B). Although this does not mimic the physiological secretion of insulin, yet it is more likely to achieve a fair glycemic control than with a single injection. The disadvantage of this regime is that it may increase the risk of hypoglycemia, especially during the middle of the night or at 3 am in response to the action of the evening dose of the intermediate acting plus regular insulin.

Twice daily insulin regimes are commonly used because of their convenience and simplicity for the patient. However, this advantage is often offset by the lack of flexibility with just two doses of insulin, adjustments for change in diet and physical activity can sometimes be difficult. This is especially applicable to the school going children and adolescent, where often they have no control over either their meal timings or exercise schedule. The hypoglycemic effect of the intermediate acting insulin mandates scheduling lunch and dinner at fairly precise times, in addition to breakfast, mid morning and mid afternoon snacks. The dietary context of each meal, especially of carbohydrates must be kept fairly constant in order to avoid hypoglycemia. Unscheduled physical activity or exercise can make such children especially prone for hypoglycemia.

Quite often when NPH or Lente insulin is given before dinner, the peak action and duration are too short to last throughout the night, resulting in hypoglycemia at about 3am and hyperglycemia in the early morning (11). In addition, hepatic glucose output in the early morning hours increases in association with an increase in the basal insulin requirement, which is thought to be the consequence of pulses of growth hormone secreted a few hours after onset of sleep. The problem, often teemed as "DAWN PHENOMENON", results in elevated fasting blood glucose. The situation can be partially remedied by giving the intermediate acting insulin at bedtime, rather than before dinner. Alternatively ultra Lente insulin can be given before dinner. However this often complicates the issue as the patient has to use these different types of insulin in a day.