Can a faulty injection technique lead to a localized insulin allergy?
Patient is a 38-year-old female diagnosed as a case of diabetes mellitus (DM) presented with neuropathic symptoms in a clinic outside our hospital with an initial fasting plasma glucose (FPG): 256 mg/dl, postprandial plasma glucose (PPG): 426 mg/dl. She was put onto inj. premixed insulin (30/70) 12 IU before breakfast and 6 IU before dinner along with metformin 500 mg twice daily after meals (BDPC). A standard 1,200 kCal/day, diabetic diet, and exercise were also advised. She presented to our outpatient department (OPD) 2 months later with a complain of redness and itching at the injection site after administration of insulin (noticed for last 3-4 month after she changed her insulin brand), and burning sensation in both feet specially during the night. She had no family history of DM, no significant past illness (including bronchial asthma), no history of any drug/food allergy. Insulin was administered by her 20-year-old daughter, and she never practiced self-monitoring of blood glucose (SMBG). On examination, her body mass index (BMI) was 22.37 kg/m2, she had no acanthosis nigricans/skin tag. Other general and systemic examinations revealed no abnormality. She had no sensory loss on 10-g monofilament test and normal ankle brachial index (ABI) values. But her insulin injection sites (over abdomen and thighs) showed multiple pigmented areas with small scars and few urticarial patches [Figures and ]. She had no lipoatrophy or lipohypertrophy at the injection site.\nHer investigations revealed complete blood count (CBC) within normal limit, serum (Sr.) creatinine 0.9 mg/dl, Sr. lipid parameters within normal limit, ultrasonography (USG) abdomen was normal, and present glycemic status: FPG = 201 mg/dl and PPG = 310 mg/dl. When her daughter was enquired about the insulin injection technique, she demonstrated a faulty technique. She used to insert the needle horizontally (not vertically) with the plane of skinfold making an intradermal injection instead of a subcutaneous one [].