Background: MODY is monogenic. About 1% of diabetes has a monogenic cause but is frequently misdiagnosed as DM1 or DM2.
Objective and hypotheses: It is important to study family history of patients with atypical diabetes forms for verification of diagnosis and prognosis.
Method: Genetic, biochemical and hormonal testing, 2 patients were examined.
Results: At pre-school medical examination a general practitioner noticed positive family history of diabetes of an 8 year old boy and sent him to an endocrinology centre. It was noted that the probands father had fasting hyperglycaemia without symptoms of diabetes and obesity at the age of 18. He was not examined for 16 years as he did not have any diabetes symptoms. When he was 34, occasionally FPG 7.4 mmol/l and after meal 12.3 mmol/l without ketosis was detected. He was diagnosed DM1 and insulin was prescribed. At the moment of examination he had diabetes for 6 years and received insulin in dose 0.1 U/kg/day. HbA1c was 6.6%. FPG was 6.6 mmol/l, stimulated glucose (after standard carbohydrate breakfast without insulin injection) was 14 mmol/l (1 h), 12.8 mmol/l (2 h). Basal insulin serum was 2.4 U/l, stimulated insulin serum was 20.9 U/l (1 h), 23.7 U/l (2 h). The boys paternal grandmother had GDM at the age of 23 years. At the moment of examination she had diabetes for 40 years without complications and received insulin in dose 32 U/d (0.5 U/kg/day). Her two sisters had DM. At the moment of examination the proband did not have hyperglycaemia and diabetes symptoms. FPG was 4.2 mmol/l, stimulated glucose (OGTT) was 7.7 mmol/l (1 h), 6.4 mmol/l (2h). Basal insulin serum was 4.2 U/l, stimulated insulin serum was 13.7 U/l (1 h), 10.3 U/l (2 h). Genetic testing revealed that the proband and his father had mutation S355X in the HNF1A gene. The probands father was prescribed sulphonylurea tablets instead of insulin and this resulted in glycaemia stabilization.
Conclusion: Correct genetic diagnosis is important for proper patients treatment and prognosis and it enables predictive genetic testing for their asymptomatic relatives.
01 - 03 Oct 2015
European Society for Paediatric Endocrinology