Insulin is a hormone naturally produced by the pancreas, playing a crucial role in regulating blood sugar levels by helping cells absorb glucose for energy. Many individuals with diabetes need to inject insulin because their bodies either do not produce enough of it or cannot use it effectively. Oral insulin is not an option as digestive enzymes would break it down before it could enter the bloodstream. Proper injection technique and careful site selection are important for ensuring the insulin is absorbed correctly and to minimize discomfort.
Optimal Injection Sites
Insulin must be injected into the subcutaneous fatty tissue, just beneath the skin, not into muscle. Muscle injection can cause rapid absorption, leading to unpredictable blood sugar levels and painful injections. Several body areas are suitable for insulin injection due to accessible fatty tissue.
The abdomen is often the preferred site because insulin is absorbed most quickly and predictably there, and it is generally easy to reach. When injecting into the abdomen, choose a spot between the bottom of the ribs and the pubic area, avoiding the two-inch region directly around the navel. The upper arms, specifically the fatty area on the back of the arm between the shoulder and elbow, are also effective sites, though absorption is somewhat slower than from the abdomen. The top and outer areas of the thighs, about four inches down from the top of the leg and four inches up from the knee, are viable options, offering a slower absorption rate compared to the abdomen or arms. The upper outer buttocks can also be used, providing the slowest absorption among the recommended sites.
Site Rotation and Selection
Regular rotation of injection sites is important to prevent lipohypertrophy, a condition where lumps of fat and scar tissue build up under the skin due to repeated injections. These lumps can interfere with insulin absorption, leading to inconsistent blood sugar control. To effectively rotate sites, a systematic pattern should be followed.
Within a chosen body area, each new injection should be at least one inch, or about two finger-widths, away from the previous injection site. One practical method involves dividing an injection area, such as the abdomen, into four quadrants and rotating through these sections. For instance, an individual might use one quadrant for a week before moving clockwise to the next. When selecting a specific spot within a site, it is important to avoid areas with scars, moles, skin blemishes, inflammation, or directly over broken blood vessels and varicose veins. Furthermore, injecting into a body part that will be exercised immediately afterward should be avoided, as increased blood flow during activity can accelerate insulin absorption.
Preparing for Injection
Proper preparation ensures safety and effectiveness before administering an insulin injection. Wash hands thoroughly with soap and water. Inspect the insulin product; check the label for the correct type and verify the expiration date. Clear insulin should appear clear, while cloudy insulin, such as NPH or premixed types, should be uniformly milky; if settled, gently roll the pen or vial between the palms to mix it, but never shake vigorously. Do not use any insulin that looks discolored, has clumps, or appears different from its usual appearance.
Prepare the injection device: for insulin pens, attach a new needle for each injection and prime the pen by dialing two units and pressing the plunger until a drop of insulin appears at the needle tip. For syringes, draw air into the syringe equivalent to the insulin dose, inject this air into the insulin vial, then invert the vial and draw the correct insulin dose. Clean the chosen injection site on the skin with an alcohol swab and allow it to air dry before injecting. Gently pinch a one to two-inch fold of skin and insert the needle at a 90-degree angle (or 45 degrees if advised by a healthcare provider for very thin individuals). After injecting the insulin, hold the needle in place for five to ten seconds before withdrawing it to ensure full dose delivery and prevent leakage.