Awareness is key to preventing lipohypertrophy in diabetic patients on insulin

A study on adult patients with type 2 diabetes mellitus (T2DM) treated with insulin for at least 6 months showed 2-in-5 patients had lipohypertrophy. The study is the first to provide local data on lipohypertrophy among diabetic patients in the primary care setting.

Lipohypertrophy, or thickened rubbery lesions, are formed due to repeated insulin injections at the same spot with needle reuse. The combination of microtrauma and the growth-promoting effect of insulin on the damaged cells gives rise to hypertrophy of the adipose tissue. During physical examination of patients, these lesions are usually palpable rather than visualized. Apart from skin disfigurement, lipohypertrophy also causes impaired insulin absorption. Reduced or delayed insulin absorption leads to an increase in the total daily dose of insulin thus increasing healthcare costs. [Malays Fam Physician 2023;18:37]*

The cross-sectional study involved 506 patients at six public primary care clinics—four located in urban areas and two in suburban areas—in central Peninsular Malaysia. More than half (51.4 percent) of the patients were aged ≥60, almost two-thirds (63.2 percent) had T2DM for ≥10 years, and 45.1 percent had been using insulin for ≥5 years. While the mean insulin dose was 0.67 units per kg body weight, only 15.2 percent had HbA_1c ≤7 percent. [Malays Fam Physician 2023;18:37]

Upon physical examination, the study researchers found lipohypertrophy in 200 patients (39.5 percent, 95 percent CI=35.2–43.9 percent), which is consistent with the prevalence reported in the Worldwide Injection Technique Questionnaire (ITQ) Study (30.8 percent) and meta-analysis by Deng et al (38 percent). [Mayo Clin Proc 2016;91(9):1212–1223; J Diabetes Investig 2017;9(3):536–543] The lesion size ranged from 5 to 60 mm (mean=17.07+11.88 mm). While 38 patients knew they had lipohypertrophy, 158 disclosed that they had injected insulin into the lesion.

Larger number of injections per day, longer needle length, repeated use of needles, incorrect rotation of injection site, longer duration of insulin use, higher total insulin dose, and higher HbA_1c level were significantly associated with lipohypertrophy. However, the multivariate analysis showed incorrect rotation of the injection site was the only factor that was significantly associated with lipohypertrophy. Overall, the study findings were consistent with the current knowledge of the aetiopathogenesis of lipohypertrophy which includes injection trauma and persistent exposure of the injection site to insulin.

Previous interventional studies conducted in France and the UK showed education and training can correct specific errors such as repeated use of needles and wrong choice of needles and can emphasize the importance of correct rotation of the injection site. [Diabetes Technol Ther 2017;19(11):623–632; Diabetes Res Clin Pract 2017;126:248–253] Using the 4-mm needle length for adults is ideal because it is proven to be equally efficacious as longer needles in glycaemic control. It also has added benefits of less pain and lower risk of intramuscular injection at all injection sites thus enabling enhanced rotation of injection sites. [Diabetes Technol Ther 2017;19(11):623–632]

With regard to the local study findings, the researchers highlighted the importance of assessing patients’ injection technique in addition to educating and training patients and healthcare professionals to prevent lipohypertrophy.