Endocrine Abstracts

Hyperglycemia in a 27–year–old woman without obesity was found in the first trimester of her third pregnancy in 2015 (fasting plasma glucose – 5.8 mmol /l). Gestational diabetes was established and insulin was initiated in basal–bolus regimen. After delivery the blood glucose was normal due two months then hyperglycemia increased to 15 mmol/l. Metformin and glimepiride were prescribed within effect. Then insulin detemir (8 U/day) was prescribed with DPP–4 inhibitor sitagliptin and SGLT2 inhibitor empagliflozin. In 2016 analysis for all antibodies were negative, the fasting C–peptide was 553 pmol/l (normal: 298–2350 pmol / l) and 1129 – postprandial. Molecular genetic testing was done in 2017. Mutation in the HNF1B gene (rs138986885) (MODY5) was diagnosed. In addition it was found that the patient is carrier of heterozygous variant rs2476601 in the tyrosine phosphatase gene (PTPN22) which is associated with an increased risk of developing type 1 diabetes mellitus (T1DM). No other clinical phenotypes associated with mutations in HNF1B were found. No other cases of diabetes in relatives have been reported. The same mutation in the HNF1B gene was found in mother and daughter of a proband with normal level of glucose when examining family members. In 2018 blood glucose level was 16 mmol/l, concentration of C–peptide decreased to 83 pmol/l. Tableted therapy was canceled and baseline bolus insulin therapy was started. In 2019 HbA1c level was 7.13%. Further decrease in pancreatic cell function was noted: fasting C–peptide 33.3 pmol/l, after eating 91.9 pmol/l. The patient was transfer to pump insulin therapy. Clinical case shows a rare combination of two types of diabetes mellitus with progressive, aggressive course of disease.