By Nora Saul
M.S., R.D., L.D.N., C.D.E.
Manager of Nutritional Education at Joslin Diabetes Center
Is there a proper way to give an insulin injection? Yes, according to a report that came out of the Third Injection Technique workshop in Athens (TITAN) in September 2009.
Prior to this report there was very little consensus on the proper way to inject insulin and even less research available to back it up.
Health practitioners like to use evidenced-based guidelines as the foundation for the recommendations we give to patients. That means that we have the results of controlled research studies at our disposal.
But medicine is both an art and a science, and although we would like to have research to back up our decisions sometimes ,we often rely on consensus statements or fall back on prior personal experience. Until recently there was little standardization across the country on how to best teach patients to give an injection. In September of last year, the Journal Diabetes & Metabolism published a special issue devoted to the results from the TITAN workshop on injection recommendations for patients with diabetes.
One hundred and twenty-seven injection experts from around the world reviewed 157 articles and the survey results of 4300 insulin-injecting patients with diabetes and came up with a set of new recommendations.
These recommendations have not been accepted universally, but we at Joslin Diabetes Center are in the processing of looking at our own procedures in light of them.
Why We Need Standards – Results of the Injection Survey
- 21% of patients admitted injecting into the same site for a whole day or even for a few days.
- 50% of patients had symptoms suggestive of lipohypertrophy (a lump under the skin caused by accumulation of extra fat at the site of many subcutaneous injections of insulin).
- 35% of patients using NPH don’t remix it prior to use.
Why it is important to Inject Properly?
The goal of injection is to deliver the insulin to the subcutaneous fatty tissue. Injection into the skin or the muscle is painful and alters insulin absorption rates.
Repeated injections over the same tissue sites can lead to lipohypertrophy (a lump of fatty tissue under the skin caused by multiple injections in the same site). Lipohypertrophy can also cause changes in the action or timing of insulin delivery.
Good News – Shorter Needles–4, 5 and 6 mm–do the job just fine
Although the depth of subcutaneous fat varies from person to person, based on their BMI, sex and body site, the thickness of the skin remains constant at about 1.9 to 2.4 mm across all parameters including sex, age, BMI, body site and race.
This led to the finding that any needle that is long enough to clear the skin depth would deliver insulin into the subcutaneous tissue. The reviewers concluded that there was no basis for using longer needles in patients with greater subcutaneous fat.
For all of you who like your needles as short as possible, this should come as welcome news.
Another important outcome was that the classic “pinch” taught to almost all patients is no longer considered necessary in most cases.
The purpose of the pinch, or in its new terminology “the skin fold,” was to make sure the needle was not being injected into muscle. The recommended short length needles make the pinch unnecessary in all but a few special cases—such as in patients with very little subcutaneous fat or children using 8 mm needles where the possibility of intramuscular injection is greater.
Other Study Highlights
A Straight Shot is Best
On an angle or straight-in – patients have been told to inject both ways. So which won? Straight-in, in almost all cases. No skin fold (pinch), use 90 degree—but if you use a skin fold, you should angle your injection.
Many people withdraw the pen needle from the site as soon as they have depressed the pen plunger all the way. However, this can lead to back leakage which can reduce the total amount of insulin delivered.
Counting to 10 before withdrawing the pen can prevent lose of insulin. Other important ways to improve your penmanship:
- Don’t reuse pen needles.
- Always prime the pen (spray 2 units of insulin into the air) prior to dialing the injection dose.
- Dispose of needles immediately after injection. This prevents air or other contaminants from entering the cartridge.
Match the Insulin to the Site
- Fast acting insulin (humalog, novolog, apidra) can be injected into any approved site.
- If injecting regular insulin, the abdomen should be used.
- NPH should be injected into the thigh or buttock.
A Checklist for Good Practices
Make sure you ask your health care provider to review your injection technique if you have any questions about any of the following:
- Your injecting regimen
- The choice and management of the devices used
- The choice, care and self-examination of injection sites
- Proper injection techniques (including site rotation, injection angle and possible use of skin folds)
- Injection complications and how to avoid them
- Optimal needle lengths
- Safe disposal of used sharps