Diabetes Mellitus Disease Summary

Last updated: 31 July 2026

Overview

Diabetes mellitus is a heterogenous metabolic disease that is defined in the Introduction section.

The Epidemiology section gives a detailed discussion on the cases affected by diabetes mellitus regionally and worldwide.

Genetic and environmental factors that cause diabetes mellitus are found in the Etiology section. Insulin secretion defects and effects are discussed in the Pathophysiology section.

Diabetes mellitus can be classified as type 1, type 2, gestational, and other specific types. These different types of diabetes mellitus are described in the Classification section. 

History and Physical Examination

Patients with diabetes mellitus present with classic signs and symptoms that are specific to the type of diabetes the patient has. The Clinical Presentation and Physical examination sections enumerate these signs and symptoms. In the History section, the essential information that needs to be elicited from the patient to come up with the proper diagnosis and management are mentioned.

Diagnosis

Parameters to be considered in the diagnosis of diabetes mellitus are in the Diagnosis or Diagnostic Criteria section. The need for laboratory tests included in these parameters such as HbA1c level and 2-hour plasma glucose measurement are included in the discussion.

All adults who are overweight (body mass index [BMI] of ≥23 kg/m2 for Asians) or with a waist circumference of ≥80 cm for Asian women and ≥90 cm for Asian men should be screened for diabetes mellitus especially with some of the risk factors mentioned in the Screening section.

The Laboratory Tests and Ancillaries section enumerates the tests that can be performed in assessing and evaluating the effect of the disease on the patient.

Other diseases that can cause persistent hyperglycemia and should be ruled out are listed in the Differential Diagnosis section.

Management

The overall target of the management for diabetes mellitus is to improve the quality of life and prevent complications and early death. In the Principles of Therapy section, the goals and factors to consider in choosing treatment in patients with diabetes mellitus are discussed.

Drugs that can be considered in the management of diabetes mellitus such as biguanides, glucagon-like peptide-1 (GLP-1) receptor agonists, sulfonylureas or insulin secretagogues, etc, and their effect in lowering HbA1c are enumerated and discussed in the Pharmacological Therapy section.

Lifestyle modification strategies, patient education and psychological therapies are essential parts of the management of patients with diabetes mellitus and are elaborated in the Nonpharmacological section.

Assessment of glycemic control is essential in evaluating the effects of therapy given to the patient and the Monitoring section explains these methods and the glycemic goals.  

The Complications section enumerates the effects of poor glycemic control in patients with diabetes mellitus. The section also discusses in detail the management of each complication.


Diabetes Mellitus_Disease SummaryDiabetes Mellitus_Disease Summary

Frequently Asked Questions

Who should undergo diabetes mellitus screening?
Screening is recommended for adults who are overweight, defined as BMI ≥23 kg/m² for Asians, or who have waist circumference ≥80 cm in Asian women or ≥90 cm in Asian men plus risk factors such as inactivity, family history, gestational diabetes, PCOS, insulin resistance, dyslipidemia, hypertension, cardiovascular disease, or high-risk ethnicity. Read more
What is the criteria to diagnose diabetes mellitus?
Diabetes mellitus is diagnosed by HbA1c ≥6.5%, fasting plasma glucose ≥7 mmol/L, 2-hour plasma glucose ≥11.1 mmol/L during a 75-g OGTT, or random plasma glucose ≥11.1 mmol/L in patients with classic hyperglycemic symptoms or hyperglycemic crisis. Confirmatory testing is required when typical symptoms are absent. Read more
When is insulin indicated in diabetes?
Insulin is required for type 1 diabetes and may be needed in type 2 diabetes when glycemic control remains inadequate despite non-insulin therapy. It may also be used for severe hyperglycemia, acute illness, pregnancy, perioperative care, or when symptoms of catabolism are present. Read more
What nonpharmacological measures support diabetes care?
Nonpharmacological management includes medical nutrition therapy, regular physical activity, weight management when appropriate, smoking cessation, diabetes self-management education, and support for adherence. These measures are essential throughout treatment and should be individualized according to age, comorbidities, lifestyle, and treatment goals. Read more
How is glycemic control monitored long term?
Glycemic control is assessed using blood glucose monitoring or interstitial glucose monitoring and HbA1c. HbA1c reflects average glycemia over about 3 months and should be checked regularly, with frequency based on clinical status, treatment regimen, achievement of goals, and physician judgment. Read more