Diabetes mellitus is a chronic disease. The risk of microvascular complications is correlated with hemoglobin A1c (HbA1c) level  Educating the diabetic patient to keep an HbA1c below 7% reduce the risk of long-term complications. We report the case of a 15 years old teenager, with chronical headache, referred for diabetes mellitus with a fasting glycemia of 83 mg/dl (normal < 100) and an HbA1C of 8.3% using an Ion-exchange High Performance Liquid Chromatography (HPLC, Adams A1C HA-8180V, normal 4-6%) and negative anti-islet and anti-insulin antibodies. She has no medical history and is of Bosnian descent. Her father due to persistently high HbA1c around 8.9% was diagnosed type II diabetic, is under Gliclazide, Semaglutide and Metformin. His diabetologist would like to add insulin to his treatment. He told us never had hyperglycemia on his glycemic profile. Our patient has no symptoms of diabetes. Her clinical examination is normal. Her body mass index is 22.6 kg/m2 (+0.8 sds). We controlled the HbA1c who was again 8.2%, using the same automaton (HPLC Adams A1C HA-8180V). We suspected a MODY diabetes or an interference with the HbA1c measurement. We asked the patient to perform glycemic profile which was normal during waiting for additional results who were all negative: fructosamine 261µmol/l (normal 205-285), capillary electrophoresis of hemoglobin and MODY Panel. Due to discrepancy between the results and high HbA1c level, we controlled the HbA1c with another HPLC automaton (TOSOH G8 normal 4-6%). The results were 6% for our patient and 6.13% for her father. This difference of HbA1c value between the two automata has led us to suspect an interference in the HbA1c measurement caused by an unusual hemoglobin variant. Genetic assessment of patient’s hemoglobin gene shows indeed a mutation coding for hemoglobin of Santa Juana and a deletion coding for the alpha thalassemia minor. The Santa Juana hemoglobin migrate in HPLC at the HbA1c level and interfere with his measurement. The interferences of Santa Juana hemoglobin seem less with TOSOH automaton than the Adams automaton. Because of intrinsic characteristics of automata, different degrees of interference can be observed and explaining why the HbA1c control of our patient is 6.0% and of her father still 6.12%. Existing enzymatic and immunohistochemical methods that are totally not influenced by any hemoglobin variants. The literature described only one similar adult case with T2DM. Finally, our patient has no diabetic and his father most likely not either.
15 Sep 2022 - 17 Sep 2022