Insulin and Other Medicines

What You Should Know About Insulin

Middle aged man with glasses, smiling.

Insulin helps lower blood sugar by moving sugar from the blood into the cells of your body. Once inside the cells, sugar provides energy. If your body doesn’t make enough insulin, you will need to take insulin by injection (shots). Insulin may cause weight gain for some people.

There are different kinds of insulin. Some work very quickly, some are longer acting. They all help to lower blood sugar. How fast insulin works depends on:

Insulin comes in different strengths. Most insulins in the United States are U-100 strength. Insulin is measured in units. There are special syringes for insulin with markings in “units”. The syringes come in 4 different sizes: 25 units, 30 units, 50 units, or 100 units. Insulin comes in a vial (small bottle) or in a pen. Some people use insulin pens for their shots. Insulin pens hold a cartridge of insulin and have a dial to set the number of units of insulin. They are convenient to use for people on the go.

Some people use an insulin pump to give 24 hour insulin coverage.

Soon some people will be able to use inhaled insulin. Inhaled insulin is expected to be on the market in the summer of 2006. This will be an alternative to short acting mealtime insulin.

What To Do

Developing an insulin plan that fits your lifestyle is an important part of managing your diabetes. Work with your medical provider to find the right match for you.

Your diabetes nurse educator is the key to learning:

It is important to take the exact amount of insulin you need.

Many people take 3 or more shots per day. The dose is based on daily blood sugar results.

Check the expiration date on your insulin. Once opened, insulin generally has a shelf life of 28 days at room temperature. When you open a new bottle of insulin or start a new pen, write the date that is 28 days away and throw the insulin away when you reach that date.

Using old insulin may not give you the glucose lowering effect you expect. If you get several bottles of insulin at once, keep the unopened bottles (or pens) in the refrigerator. Do NOT freeze. Keep insulin away from temperature extremes of heat and cold. If it is very hot, you should keep your insulin cool in an insulated container.

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Types of Insulin
Type Brand Begins Working Works Hardest (peaks) Stops Working
Lispro - very short acting Humalog®, Humulin® 10-15 min. 30-90 min. 4-5 Should be taken just before eating. Looks clear in bottle.
Aspart - very short acting NovoLog® 10-15 min. 40-50 min. 3-5 Should be taken just before eating (within 5-10 minutes). Looks clear and colorless in bottle.
Glulisine - very short acting Apidra® 10-15 min. 1-2 hrs 3-4 Should be taken 15 minutes before a meal and up to 20 minutes after the start of the meal.
Regular short acting   30-60 min. 2-4 hrs 6-9 Given near mealtime (about 30 minutes before eating). Looks clear in bottle. When combining Regular and NPH, draw up regular insulin first, then NPH.
NPH - moderate acting   2-4 hrs 4-8 hrs 12-16 Usually taken in the morning or before bed. Looks cloudy in bottle. There should be no lumps.
Glargine - long acting Lantus® 2-4 hrs all day up to 24 Do not mix with other insulins. Looks clear. Discard after 28 days.
Detemir - long acting Levemir® 2-4 hrs all day up to 24 Do not mix with other insulins. Looks clear. Discard after 42 days
Pre-Mixed - A mixture of long acting and short or very short acting insulins.




5-15 min.

5-15 min.

30-45 min.

4-8/1-2 hrs

4-8/1-2 hrs

4-8/2-3 hrs




Ask your medical provider about which brand of mixed insulins is good for you.

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Other Injectable Medicines: There is a new class of medicines known as “incretin mimetics” that can improve glucose control. These medicines are given by injection (a shot) similar to insulin.

Other Injectable Medicines
Medicine Brand Name Side Effects Comments
Exanatide Byetta nausea hypoglycemia Promotes weight loss. Helps lower blood sugars, especially after meals. Other diabetes medicine may need to be decreased. Can be used with metformin or sulfonylureas. It is not approved for people on insulin. May increase insulin production in the pancreas. Comes in a prefilled injector pen. Must be kept refrigerated.
Pramlintide Symlin Slight nausea hypoglycemia Decreases appetite. Slows stomach emptying. May use with insulin; not approved to use with other diabetes medicines. May need less insulin.


Insulin lowers your blood sugar whether you eat or not. The insulin you take and the food you eat must be balanced. Do not skip meals. Otherwise you can develop low blood sugar. Low blood sugar needs to be treated right away (see high and low blood sugar).

Usually insulin given in the belly is absorbed the fastest. If you will be doing exercise using the arm(s) or the leg(s), it is better to give the insulin in an area not directly being exercised. Otherwise, the insulin will be used faster. For example, if you are playing tennis, don’t inject the arm with which you swing the racquet. It is better to not take insulin just before a warm bath or shower since the warmth will cause the insulin to be absorbed faster.

If you have been taking multiple daily shots of insulin, counting your carbs and checking your blood sugar often, you might want to consider an insulin pump. An insulin pump provides a steady amount of background (basal) insulin over a 24 hour period with additional (bolus) insulin given to cover meals and snacks. Many people like the flexibility that an insulin pump provides. If you think this is something you might like, talk to your diabetes educator or medical provider.

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