What is diabetes mellitus (DM)?

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From the Guidelines

Diabetes mellitus (DM) is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both, leading to long-term damage and failure of various organs. According to the American Diabetes Association 1, diabetes is associated with chronic hyperglycemia, which can cause damage, dysfunction, and failure of different organs, especially the eyes, kidneys, nerves, heart, and blood vessels. The symptoms of diabetes include polyuria, polydipsia, weight loss, sometimes with polyphagia, and blurred vision, as well as impairment of growth and susceptibility to certain infections.

Key Characteristics of Diabetes

  • Hyperglycemia resulting from defects in insulin secretion, insulin action, or both
  • Long-term damage and failure of various organs, including the eyes, kidneys, nerves, heart, and blood vessels
  • Symptoms such as polyuria, polydipsia, weight loss, and blurred vision
  • Increased risk of atherosclerotic cardiovascular, peripheral arterial, and cerebrovascular disease

Types of Diabetes

The vast majority of cases of diabetes fall into two broad etiopathogenetic categories: type 1 diabetes, characterized by an absolute deficiency of insulin secretion, and type 2 diabetes, characterized by a combination of resistance to insulin action and an inadequate compensatory insulin secretory response 1.

Management and Complications

If left untreated, diabetes can lead to serious complications affecting the heart, blood vessels, nerves, eyes, and kidneys. Management typically involves blood sugar monitoring, medication, healthy eating, regular physical activity, and maintaining a healthy weight. Regular medical check-ups are essential for people with diabetes to monitor their condition and prevent complications 1.

From the Research

Definition of Diabetes Mellitus (DM)

  • Diabetes mellitus (DM) is a metabolic disorder characterized by the presence of chronic hyperglycemia accompanied by greater or lesser impairment in the metabolism of carbohydrates, lipids, and proteins 2.
  • It is a chronic heterogeneous metabolic disorder with complex pathogenesis, characterized by elevated blood glucose levels or hyperglycemia, resulting from abnormalities in either insulin secretion or insulin action or both 3.
  • DM is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both 4.

Characteristics of Diabetes Mellitus

  • The chronic hyperglycemia of diabetes mellitus is associated with long-term damage, dysfunction, and failure of various organs, especially the eyes, kidneys, nerves, heart, and blood vessels 4.
  • Hyperglycemia manifests in various forms with a varied presentation and results in carbohydrate, fat, and protein metabolic dysfunctions 3.
  • Chronic hyperglycemia levels lead to macrovascular and microvascular complications, including peripheral artery disease, cardiovascular diseases, cerebrovascular diseases, diabetic microangiopathy, diabetic nephropathy, diabetic retinopathy, and diabetic neuropathy 5.

Diagnosis and Classification of Diabetes Mellitus

  • Diabetes mellitus is diagnosed by blood or plasma glucose levels, with a random plasma glucose level > or = 200 mg/dL in an individual with classic symptoms, or a fasting plasma glucose level > or = 126 mg/dL or a 2-hour plasma glucose level > or = 200 mg/dL after an oral glucose challenge of 75 g on 2 occasions 6.
  • The major types of diabetes mellitus are type 1 diabetes (insulin deficient) and type 2 diabetes (combination of insulin resistance and insulin deficiency) 6.
  • Revised diagnostic criteria and classifications were agreed upon in 1997 and 1998 by the American Diabetes Association and the World Health Organization, respectively 2.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

[Diagnosis, classification and cathogenesis of diabetes mellitus].

Revista espanola de cardiologia, 2002

Research

Pathophysiology of diabetes: An overview.

Avicenna journal of medicine, 2020

Research

Diabetes mellitus.

Clinics in podiatric medicine and surgery, 2002

Research

Diagnosis, classification, and pathogenesis of diabetes mellitus.

The Journal of clinical psychiatry, 2001

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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