Cochin Cardiac Club

Health Blog by Dr.Uday Nair


Beta cells of the pancreas make the hormone insulin. With each meal, beta cells release insulin to help the body use or store the blood glucose it gets from food. In people with type 1 diabetes, the pancreas no longer makes insulin. The beta cells have been destroyed and they need insulin injections to use glucose from meals. People with type 2 diabetes make insulin, but their bodies don't respond well to it. Some people with type 2 diabetes need diabetes pills or insulin injections to help their bodies use glucose for energy 
Although most doctors agree that insulin is an efficacious approach to the management of type 2 diabetes, many still consider insulin therapy as the last resort and indicate that their patients are hesitant to take insulin.

Principles of insulin therapy

  • To provide sufficient insulin throughout the 24 h to cover basal requirements
  • To deliver higher boluses of insulin in an attempt to match the glycemic effect of meals

Injection site

Where you inject your insulin has an effect on how quickly it goes to work in your body. For example, insulin injected into your abdomen works faster than when you inject it into your thigh or buttock. It’s usually preferable to inject the insulin in the same muscle group each time so you can predict speed of delivery. But it is important that you rotate the exact location of the injection to avoid developing lumps under the skin. 

Types of Insulin

Rapid onset-fast acting insulin:

It is fast acting so starts working within one to 20 minutes. It is clear in appearance and its peak time is about one hour later and lasts for three to five hours. When you inject rapid onset-fast acting type of insulin, you must eat immediately after you inject. The two rapid onset-fast acting insulin types currently available are:
  • Novo Rapid (Insulin Aspart)
  • Humalog (Lispro)

Short acting insulin

It looks clear and begins to lower blood glucose levels within 30 minutes, so you need to take your injection half an hour before eating. Short acting insulin has peak effect of four hours and works for about six hours. Short acting insulin types, currently available include:
  • Actrapid
  • Humulin
  • Hypurin Neutral (bovine - highly purified beef insulin)

Intermediate acting insulin:

Intermediate acting insulin looks cloudy. They have either protamine or zinc added to delay their action. This insulin starts to show its effect about 90 minutes after you inject, peak at 4 to 12 hours and lasts for 16 to 24hours.
Intermediate acting insulins presently available with protamine:
  • Protaphane
  • Humulin NPH
  • Hypurin Isophane (bovine)

Mixed insulin

Mixed insulin is cloudy in appearance. It is a combination of either a rapid onset-fast acting or a short acting insulin and intermediate acting insulin. Advantage of it is that, two types of insulin can be given in one injection. When it shows 30/70 then it means 30% of short acting is mixed with 70%of intermediate acting insulin.
The mixed insulins currently available include:
  • NovoMix30
  • Humalog Mix 25
  • Mixtard 30/70
  • Mixtard 20/80
Note:Roll or shake the vial of insulin in order to mix them evenly.

Long acting insulin: 
There are two kinds of long acting insulin available in market, both with clear appearance.
  • Lantus (Glargine) - It has no peak period as it works constantly when released into your bloodstream at a relatively constant rate. (full 24 hours)
  • Levemir (Detemir) - It has a relatively flat action, can last up to 24 hours and may be given once or twice during the day.

Insulin pump:

Another method of insulin administration is via an insulin pump. This can be a complicated and expensive method but is useful for people whose blood glucose levels are difficult to control.

Which INSULIN is the best?
When glycemic control worsens or is not adequate despite the use of oral hypoglycemic agents, often the next step is to add basal insulin therapy, ie, once-daily doses of a long-acting insulin.
Most often, glargine or detemir (Levemir) insulin is used. Detemir can also be given twice daily if needed. If cost is a concern, neutral protamine Hagedorn (NPH, Humulin N, Novolin N) insulin once daily at bedtime or twice daily is a reasonable alternative.

If you have type 1 diabetes then in almost all cases you should either use an insulin pump or you should take a longer-acting insulin (NPH, Levemir, or Lantus) once (sometimes twice) daily and a rapid-acting insulin (Apidra, Humalog, or NovoRapid) before each meal. 

If you have type 2 diabetes and your main problem is an elevated blood glucose when you awaken (something called the dawn phenomenon) then taking NPH, Lantus, or Levemir, once daily, at bedtime is usually the best choice.

If you have type 2 diabetes and your blood glucose levels are elevated throughout the day (despite taking your non-insulin therapies) then the best insulin choice for most people is to take a longer-acting insulin (NPH, Levemir, or Lantus) once daily and a rapid-acting insulin (Apidra, Humalog, or NovoRapid) before those meals that are causing your after-meal blood glucose to be elevated. Alternatively, some people are sufficiently managed using a premixed insulin before breakfast and before dinner. (Premixed insulin therapy is best reserved for those people whose lives are remarkably consistent day-to-day in terms of when you get up and go to sleep, the type/intensity/duration of exercise, the meals you eat and the timing of your meals, and so on.)

Things to remember-

More short-acting insulin is usually needed when:

  • eating more than usual
  • doing less physical activity, eg-taking the car than walking to the shop.
Less short-acting insulin is needed when:
  • eating less
  • doing more physical activity.
The dose of long-acting insulin should not be adjusted as a short-term measure - for example if the blood sugar level is high on one occasion only.
This is because a change in dose doesn't change the body's glucose levels immediately and can affect sugar levels in the next few days 
Insulin resistance

Insulin resistance occurs when the normal amount of insulin secreted by the pancreas is not able to unlock the door to cells.  To maintain a normal blood glucose level, the pancreas secretes additional insulin.  In some cases involving about 1/3 of the people with insulin resistance, when the body cells resist or do not respond to even high levels of insulin, glucose builds up in the blood resulting in high blood glucose or type 2 diabetes.  Even people with diabetes who take oral medication or require insulin injections to control their blood glucose levels can have higher than normal blood insulin levels due to insulin resistance.

Insulin and weight gain

Eating healthy foods and staying physically active every day can help you prevent unwanted weight gain. 

Keep the following points in mind:
  • Eating and drinking fewer calories helps you prevent weight gain.Eat every meal with the right mix of starches, fruits and vegetables, proteins, and fats.Cut down your portion sizes,Say NO to second helpings and drink water instead of high-calorie drinks.
  • Don't try to cut calories by skipping meals.Skipping meals causes large fluctuations in blood sugar levels. Three modest meals a day with healthy snacks in between can result in better control of weight and blood glucose levels.
  • Physical activity burns calories. A reasonable goal for most adults is a minimum of 30 minutes of brisk walking.
  • Diabetes medications that help regulate blood glucose levels and may promote weight loss include — Metformin (Fortamet, Glucophage, others), Exenatide (Byetta), Liraglutide (Victoza) and Pramlintide (Symlin) . Consult with your doctor if these or other medications can be combined with your insulin therapy.
  • Don't cut down on your insulin dosages to reduce weight gain as the risks are serious. Without enough insulin, your blood sugar level will rise  and so will your risk of diabetes complications.

Please Note-
  • People with type 2 diabetes tend to be at lower risk of hypoglycemia (low blood sugar) than those with type 1. A prolonged episode of low blood sugar could cause a loss of consciousness or coma. Still, most people with type 2 can easily recognize the symptoms, which include anxiety, shaky hands, sweating, and an urge to eat. Consuming a bit of sugar,like in a candy, diluted juice, or glucose tablets—quickly reverses the low blood sugar.
  • The insulin therapy should be re-evaluated routinely. It might need to be changed in response to the dynamic multifactorial process of progression of diabetes, change in stress level, presence or resolution of intercurrent illnesses, risk of hypoglycemia, concerns about weight gain, and cost.
  • Adjustment of the therapy should be considered in response to improvement of glycemic control related to improvement of dietary management, exercising, weight loss, and medical therapies.
  • Good control of the diabetes will reduce the risk of developing long-term complications in the young. But this will require fairly intensive monitoring and adjustment of the blood sugar.

Good control in diabetes would be blood glucose consistently between 70 mg/dl and 120/dl.
This should result in a HbA1c level (long-term glucose level) of 7 per cent or less.
  • In an elderly person or someone with a limited outlook for other medical reasons, it may be inappropriate to be so precise with insulin treatment.

Instead, controlling diabetes symptoms by reducing blood sugar levels may be all that's required.
Less strict control, so blood glucose is around 180 mg/dl, may be good enough to stop symptoms such as thirst and the frequent desire to pass urine.
Measure your blood sugar every day to learn how to react to eating, exercise and changes in insulin dosage. This is the only way to get a good feel for, and control of, blood glucose levels.

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