Background: Lipohypertrophy (LH) is harmful and requires early diagnosis. While LH is typically detected by inspection and palpation (physical examination), the reliability is potentially low. We evaluated the prevalence and contributing risk factors for missed LH compared to ultrasound scanning (USS).

Methods: This was a cross-sectional study included 260 patients who had injected insulin continuously for at least 1 year. Physical examination and USS were used meanwhile. Associations between missed diagnosis and clinical, injection behavioral variables were examined.

Results: Patients were 40.4 ± 23.7 years old, 52.7% male, 50.8% type 1 diabetes. 80.8% were diagnosed with LH by USS, that three characteristics are significant thickening of the subcutaneous fat layer; increased echogenicity in diffuse areas; nodular hyperechoic foci. Physical examination resulted in a 39.0% false negative rate. By stepwise logistic regression, duration of insulin therapy modestly associated with missed diagnosis of LH (odds ratios [OR] = 0.84, P < 0.001); Higher BMI and correct site rotation showed ORs of 3.02 (P = 0.005) and 3.67 (P < 0.001), respectively.

Conclusions: Physical examination was associated with a high rate of missed LH diagnosis for patients received insulin for a short duration, higher BMI etc. Ultrasound scanning should be used as a complementary technique.

J. Xu: None. D. Luo: None. H. Wang: None. M. Zhu: None. Y. Shi: None.

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