JPSIM Journal of Pakistan Society of Internal Medicine J Pak Soc Intern Med 2709-8729 2710-0804 Pakistan Society of Internal Medicine 10.70302/jpsim.v3i4.2267 jpsim.v3i4.2267 Case Report Atypical Presentation of Diabetes Mellitus Aziz Abdul Vohra Laiba Imran Khan Sajjad Ali sajjadali_kmcite@yahoo.com * Ram Nanik Aga Khan University Hospital, Karachi Ziauddin University, Karachi *Correspondence: Sajjad Ali Khan (sajjadali_kmcite@yahoo.com) 18 12 2022 2022 3 4 339 341 24 07 2022 30 09 2022 Copyright © 2022 The Author(s) 2022 The Author(s) https://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction

Maturity onset diabetes of the young (MODY) is a subtype of diabetes of autosomal dominant inheritance characterized by anomalous B cell activity, decreasing insulin production ability of the pancreas for glucose utilization, and an early onset of hyperglycemia typically presenting before the age of 25.1 It consists of a genetically heterogeneous group of monogenic disorders having more than 10 variants.2

Patients with this kind of diabetes are frequently misdiagnosed as having either type 1 or type 2 diabetes mellitus (DM). Unlike DM1 and DM2 which are polygenic, MODY is caused by a single gene mutation including Glucokinase (GCK), Hepatocyte Nuclear Factor (HNF1A, HNF4A, HNF1B), Insulin (INS), NEURO1, Pancreatic and Duodenal Homeobox (PDX1), Paired box (PAX4), ATP Binding Cassette Subfamily C Member (ABCC8), Potassium Inwardly Rectifying Channel Subfamily J Member 11 (KCNJ11), Krüppel-like family of transcription factors (KLF11), Carboxyl Ester Lipase (CEL), Tyrosine-protein kinase BLK (BLK), and Amyloid Beta Precursor Protein (APPL1) diagnosed by molecular genetic testing out of which mutations in hepatocyte nuclear factor (HNF)4A (MODY1), glucokinase (GCK) (MODY2), and HNF1A (MODY3) genes total to almost 99% of the cases.3,4

Mild, asymptomatic hyperglycemia in a child, adolescent, or young adult with a family history of autosomal dominant diabetes is the most common symptom of MODY.5 Patients with mutations in HNF1A and HNF4A are more likely to have polydipsia and polyuria, however, those with mutations in GCK are more likely to have a moderate increase in blood glucose on standard testing.5

MODY-HNF1A is most prevalent in the UK, Netherlands, and Denmark, whereas Spain, Italy, France, Germany show a higher occurrence of MODY-GCK. 6 Even though Asian patients have a higher prevalence of diabetes, their limited referral for UK MODY testing underrepresents them.7 The estimated incidence of MODY in children and adolescents under the age of 15 with newly diagnosed DM is 2.4% for which glucose-lowering medications such as sulfonylureas, meglitinides, and insulin in combination with a low carbohydrate diet have been set as the standard treatment.8,9

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