Type 2 diabetes mellitus in adults

Last reviewed: 27 Dec 2022
Last updated: 16 Dec 2022



History and exam

Key diagnostic factors

  • asymptomatic
  • polydipsia
  • polyuria
  • unintentional weight loss
  • polyphagia
  • hyperglycemic crisis
More key diagnostic factors

Other diagnostic factors

  • fatigue
  • blurred vision
  • nocturia
  • candidal infections
  • skin infections
  • urinary tract infections
  • paresthesias
  • acanthosis nigricans
Other diagnostic factors

Risk factors

  • older age
  • overweight/obesity
  • gestational diabetes
  • prediabetes
  • first-degree relative with type 2 diabetes
  • African, Latino, or American-Indian ancestry
  • physical inactivity
  • polycystic ovary syndrome (PCOS)
  • hypertension
  • dyslipidemia
  • cardiovascular disease
  • stress
More risk factors

Diagnostic investigations

1st investigations to order

  • fasting plasma glucose
  • HbA1c
  • 2-hour plasma glucose
  • random plasma glucose
More 1st investigations to order

Investigations to consider

  • urine ketones
  • random C-peptide
  • autoantibodies
  • urinary albumin excretion
  • serum creatinine and estimated GFR
  • fasting lipid profile
  • ECG
  • ankle-brachial index (ABI)
  • toe-brachial index (TBI)
  • dilated retinal examination
  • liver function test
More investigations to consider

Treatment algorithm


at initial diagnosis


marked hyperglycemia nonpregnant: serum glucose ≥300 mg/dL or HbA1c >10% or symptomatic

without marked hyperglycemia nonpregnant asymptomatic: serum glucose <300 mg/dL or HbA1c <10%




Gregg Simonson, PhD

Director Professional Training

International Diabetes Center at Park Nicollet




GS is a member of the Merck scientific advisory board. He receives no personal income from Merck and all honorarium goes to his employer, the non-profit International Diabetes Center, part of the HealthPartners Institute. GS has received unrestricted educational grants from Sanofi and Abbott Diabetes Care to conduct continuing medical education programs.

Anders Carlson, MD

Medical Director

International Diabetes Center at Park Nicollet




HealthPartners Institute/International Diabetes Center employs AC and has contracts with Abbott Diabetes Care, Dexcom, Eli Lilly, Insulet, Medscape, Medtronic, Novo Nordisk, Sanofi US Services, Inc., and United Healthcare for his services as a research investigator and/or consultant. AC receives no personal income from any of these services. AC is an author of a number of references cited in this topic.

Thomas Martens, MD

Medical Director

International Diabetes Center at Park Nicollet




TM has been a site principal investigator and subprincipal investigator for research with funding from Abbott Diabetes Care, Dexcom, Medtronic, Insulet, Eli Lilly, and Novo Nordisk, without being personally reimbursed. TM has participated speaking engagements arranged and managed by his employer, International Diabetes Center and funded by Abbott Diabetes Care, Eli Lilly, Novo Nordisk, Medtronic, Medscape, American Diabetes Association, American Medical Group Association and American College of Physicians. All financial payments for the research activities and the speaking and medical education activities were to HealthPartners Institute DBA International Diabetes Center. TM is paid on a salary and does not receive direct payments for any of these activities. TM has co-authored an article with individuals employed by Eli Lilly and Dexcom. He is an author of a number of references cited in this topic.

Richard Bergenstal, MD

Executive Director

International Diabetes Center at Park Nicollet




RB has received research or grant support, has acted as a consultant, or has been on the scientific advisory board for Abbott Diabetes Care, DexCom, Eli Lilly, Helmsley Charitable Trust, Insulet, Medtronic, NIH/NIDDK, Novo Nordisk, and Sanofi. RB served as a consultant for Ascencia, Bigfoot Biomedical, Inc., CeQur, Hygieia, Onduo, Roche Diabetes Care, Zealand Pharma, and United Healthcare. RB's employer, non-profit HealthPartners Institute, contracts for his services and he receives no personal income. He is the co-author of some references cited in this topic.


Dr Gregg Simonson, Dr Anders Carlson, Dr Thomas Martens, and Dr Richard Bergenstal would like to gratefully acknowledge Dr Patrick J. O'Connor and Dr JoAnn M. Sperl-Hillen, previous contributors to this topic.


PJO receives research funding from the National Institutes of Health on multiple projects. JMS-H is an inventor on a US patent for Disease Treatment Simulation, a simulation-based technology developed without commercial support to educate health providers on chronic disease management in a virtual environment. PJO and JMS-H are authors of a number of references cited in this topic.

Peer reviewers

David K. McCulloch, MD

Medical Director

Clinical Improvement Group Health Cooperative




DKM declares that he has no competing interests.

Ashim K. Sinha, MBBS, MD, FRACP, FACE

Associate Professor

Director of Diabetes and Endocrinology

Cairns Base Hospital and Diabetes Centre




AKS declares that he has no competing interests.

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