A Review on Diabetes Mellitus

Abstract

Diabetes mellitus has become a major global health issue due to its rising prevalence. This review discusses the definition and classification of diabetes, including type 1 diabetes (both idiopathic and fulminant), type 2 diabetes, and gestational diabetes. It also highlights important terms and abbreviations related to diabetes, its causes, complications, and the biological processes involved. Diabetes mellitus is one of the most widespread non-communicable diseases globally. In India, managing diabetes presents several challenges, such as increasing cases in both cities and villages, low public awareness, limited healthcare access, high treatment costs, poor blood sugar control, and growing complications. Insulin is usually given through subcutaneous injections several times a day, which can be uncomfortable and affects how well patients stick to their treatment. Although type 1 diabetes is becoming more common, type 2 diabetes is the main driver of the diabetes epidemic, making up over 90% of all cases. Type 2 diabetes is a serious long-term condition caused by a mix of genetic and environmental factors, along with risks like obesity and lack of physical activity. Many medical terms and short forms are connected to diabetes and related health problems. Some of these include methylamine-N-oxide, which affects metabolism, and NAFLD, a type of liver disease common in diabetes. Other related issues include NASH, hepatitis C virus (HCV), and kidney damage caused by contrast agents (CIN). Kidney function is checked using GFR. Proteins like TGF-?1 and the JAK-STAT pathway help explain how these diseases develop. Other proteins like SMPDL3b, JAML, and CaMKII help cells function properly, while SERCA2a controls calcium inside cells. Gene activity can also be affected by HDACs. Immune cells (PBMCs) and signals like HIF1? and VEGF-1 are linked to inflammation and blood vessel growth. Blood vessel health is supported by proteins like VE-cadherin and Ang1. Good fats like EPA and DHA are important for heart and brain health. Molecules such as 12-HETE, DPP4 inhibitors (used to treat diabetes), and proteins like ApoE, HCN2, NT-3, NGF, and NTR are involved in nerve, heart, and metabolic functions.

Introduction

Diabetes mellitus is a chronic metabolic disorder characterized by high blood glucose levels caused by insufficient insulin production, insulin resistance, or both. It is classified into type 1 diabetes (T1D), type 2 diabetes (T2D), and other specific forms including gestational diabetes, with T2D accounting for the vast majority of cases (~96%). T2D is strongly associated with insulin resistance, progressive loss of pancreatic β-cell function, obesity, and lifestyle factors such as poor diet and inactivity, though its exact cause remains unclear.

Type 1 diabetes is an autoimmune disease in which the immune system destroys insulin-producing β-cells, leading to absolute insulin deficiency. It often develops gradually but ultimately requires lifelong insulin therapy. Rare subtypes include idiopathic T1D and fulminant T1D, which progress rapidly and may be linked to genetic or viral triggers. Despite treatment advances, patients still face complications such as blood sugar instability, cardiovascular and kidney disease, and psychological stress.

Type 2 diabetes develops when the body’s tissues become less responsive to insulin and the pancreas gradually fails to compensate. It is strongly influenced by genetics and lifestyle factors like obesity and physical inactivity. Both T1D and T2D involve complex pathophysiological mechanisms including inflammation, oxidative stress, hormonal imbalance, and impaired cellular signaling pathways, which worsen insulin resistance and β-cell dysfunction over time.

Conclusion

This review and our ideas aim to help newly diagnosed patients with type 2 diabetes (T2D) who are undergoing blood sugar-lowering treatment. The causes of T2D are not fully clear, and there is no cure yet. However, T2D and related organ damage caused by metabolic dysfunction syndrome (MDS) can be prevented. Important steps include preventing and treating early overweight, obesity, and metabolic-associated fatty liver disease (MASLD), which can greatly reduce the chance of developing T2D. If prevention fails, it is important to detect diabetes early. Once diagnosed, treatment should focus on protecting organs by managing MDS because most people with T2D also have MDS. This article does not cover emergency conditions like diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS), nor does it discuss treatment for elderly patients, pregnant women with gestational diabetes, or patients with both T2D and cardiovascular disease. T2D itself is a simple condition, but patients often have more complex health issues because many develop MDS. T2D usually comes after preobesity, obesity, and MASLD. Therefore, terms like “complications” should be used carefully, especially for kidney disease (DKD) or large blood vessel problems. If not, treatment might wrongly focus only on controlling blood sugar. To improve patients\' quality and length of life, managing MDS as a whole is necessary, not just focusing on blood sugar control.

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Copyright

Copyright © 2026 Gaurav Sunil Shelke, Aryan Ashok Gonjari, Virajas Kailas Ghatge, Guide Mr. Vetal Nana Kodalkar, Guide Dr. Naga Raju Potnuri. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.