Skip to main content
        
        U.S. flag
                An official website of the United States government
                    Here’s how you know
                Here’s how you know**Official websites use .gov**
                        
                        A **.gov** website belongs to an official government organization in the United States.
            **Secure .gov websites use HTTPS**
                        
                        A **lock** (
                        Locked padlock icon
                        ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.Search
    Menu

        Search for Information from NIDDK
            
            Entire Site
                Research & Funding
                Health Information
                News
                About NIDDKSearch

Home
            Research & Funding
                                Expand Research & Funding
                                Current Funding Opportunities
                                                    Research Programs & Contacts
                                                    Human Subjects Research
                                                    Funding Process
                                            Research Training & Career Development
                                                    Funded Grants & Grant History
                                                    Research Resources
                                            Research at NIDDK
                                                    Technology Advancement & Transfer
                                                    Meetings & Workshops
                        Health Information
                                Expand Health Information
                                Health Topics
                                                                                                    Diabetes
                                                    Digestive Diseases
                                                    Kidney Disease
                                                    Weight Management
                                                    Liver Disease
                                                    Urologic Diseases
                                                    Endocrine Diseases
                                                    Diet & Nutrition
                                                    Blood Diseases
                                                    Diagnostic Tests
                                            La información de la salud en español
                                                    Health Statistics
                                                    Healthy Moments Radio Broadcast
                                                    Clinical Trials
                                            For Health Professionals
                                                    Diabetes Discoveries & Practice Blog
                                                    Community Health & Outreach
                        News
                                Expand News
                                News Archive
                                                    For Reporters
                                            Meetings & Workshops
                                                    Media Library
                                            Follow Us
                        About NIDDK
                                Expand About NIDDK
                                Meet the Director
                                                    Offices & Divisions
                                                    Staff Directory
                                                    Budget & Legislative Information
                                            Advisory & Coordinating Committees
                                                    Strategic Plans & Reports
                                                    Research Areas
                                                    FAQs
                                            Jobs at NIDDK
                                                    Visit Us
                                                    Contact Us Home
                    Health Information
                    Diabetes
                    Diabetes Overview
                    Symptoms & Causes

    Related Topics
    English
        English
                Español
        Diabetes Overview
        What Is Diabetes?
Show child pages
        Type 1 Diabetes
                Type 2 Diabetes
                Insulin Resistance & Prediabetes
                Gestational Diabetes
                Monogenic Diabetes
                Symptoms & Causes
                Risk Factors for Type 2 Diabetes
Show child pages
        Diabetes Risk Test
                Preventing Type 2 Diabetes
Show child pages
        Your Game Plan to Prevent Type 2 Diabetes
                Diabetes Tests & Diagnosis
                Managing Diabetes
Show child pages
        Artificial Pancreas
                Continuous Glucose Monitoring
                Insulin, Medicines, & Other Diabetes Treatments
Show child pages
        Pancreatic Islet Transplantation
                Healthy Living with Diabetes
                Preventing Diabetes Problems
Show child pages
        Diabetes, Heart Disease, & Stroke
                Low Blood Glucose (Hypoglycemia)
                Diabetic Neuropathy
                Diabetic Kidney Disease
                Diabetes & Foot Problems
                Diabetic Eye Disease
                Diabetes, Gum Disease, & Other Dental Problems
                Diabetes, Sexual, & Bladder Problems
                Clinical TrialsSymptoms & Causes of Diabetes
**In this section:**
What are the symptoms of diabetes?
    What causes type 1 diabetes?
    What causes type 2 diabetes?
    What causes gestational diabetes?
    What else can cause diabetes?What are the symptoms of diabetes?

Symptoms of diabetes include
increased thirst and urination
    increased hunger
    fatigue
    blurred vision
    numbness or tingling in the feet or hands
    sores that do not heal
    unexplained weight lossSymptoms of type 1 diabetes can start quickly, in a matter of weeks. Symptoms of type 2 diabetes often develop slowly—over the course of several years—and can be so mild that you might not even notice them. Many people with type 2 diabetes have no symptoms. Some people do not find out they have the disease until they have diabetes-related health problems, such as blurred vision or heart trouble.
What causes type 1 diabetes?

Type 1 diabetes occurs when your immune system, the body’s system for fighting infection, attacks and destroys the insulin-producing beta cells of the pancreas. Scientists think type 1 diabetes is caused by genes and environmental factors, such as viruses, that might trigger the disease. Studies such as TrialNet are working to pinpoint causes of type 1 diabetes and possible ways to prevent or slow the disease.
What causes type 2 diabetes?
Type 2 diabetes—the most common form of diabetes—is caused by several factors, including lifestyle factors and genes.
Overweight, obesity, and physical inactivity
You are more likely to develop type 2 diabetes if you are not physically active and are overweight or have obesity. Extra weight sometimes causes insulin resistance and is common in people with type 2 diabetes. The location of body fat also makes a difference. Extra belly fat is linked to insulin resistance, type 2 diabetes, and heart and blood vessel disease. To see if your weight puts you at risk for type 2 diabetes, check out these Body Mass Index (BMI) charts.
Insulin resistance
Type 2 diabetes usually begins with insulin resistance, a condition in which muscle, liver, and fat cells do not use insulin well. As a result, your body needs more insulin to help glucose enter cells. At first, the pancreas makes more insulin to keep up with the added demand. Over time, the pancreas can’t make enough insulin, and blood glucose levels rise.
Genes and family history
As in type 1 diabetes, certain genes may make you more likely to develop type 2 diabetes. The disease tends to run in families and occurs more often in these racial/ethnic groups:
African Americans
    Alaska Natives
    American Indians
    Asian Americans
    Hispanics/Latinos
    Native Hawaiians
    Pacific IslandersGenes also can increase the risk of type 2 diabetes by increasing a person’s tendency to become overweight or have obesity.
What causes gestational diabetes?
Scientists believe gestational diabetes, a type of diabetes that develops during pregnancy, is caused by the hormonal changes of pregnancy along with genetic and lifestyle factors.
Insulin resistance
Hormones produced by the placenta contribute to insulin resistance, which occurs in all women during late pregnancy. Most pregnant women can produce enough insulin to overcome insulin resistance, but some cannot. Gestational diabetes occurs when the pancreas can’t make enough insulin.
As with type 2 diabetes, extra weight is linked to gestational diabetes. Women who are overweight or have obesity may already have insulin resistance when they become pregnant. Gaining too much weight during pregnancy may also be a factor.
Photo of smiling pregnant womanHormonal changes, extra weight, and family history can contribute to gestational diabetes.Genes and family history
Having a family history of diabetes makes it more likely that a woman will develop gestational diabetes, which suggests that genes play a role. Genes may also explain why the disorder occurs more often in African Americans, American Indians, Asians, and Hispanics/Latinas.
What else can cause diabetes?

Genetic mutations, other diseases, damage to the pancreas, and certain medicines may also cause diabetes.
Genetic mutations
Monogenic diabetesis caused by mutations, or changes, in a single gene. These changes are usually passed through families, but sometimes the gene mutation happens on its own. Most of these gene mutations cause diabetes by making the pancreas less able to make insulin. The most common types of monogenic diabetes are neonatal diabetes and maturity-onset diabetes of the young (MODY). Neonatal diabetes occurs in the first 6 months of life. Doctors usually diagnose MODY during adolescence or early adulthood, but sometimes the disease is not diagnosed until later in life.
    Cystic fibrosis produces thick mucus that causes scarring in the pancreas. This scarring can prevent the pancreas from making enough insulin.
    Hemochromatosis causes the body to store too much iron. If the disease is not treated, iron can build up in and damage the pancreas and other organs.Hormonal diseases
Some hormonal diseases cause the body to produce too much of certain hormones, which sometimes cause insulin resistance and diabetes.
Cushing’s syndrome occurs when the body produces too much cortisol—often called the “stress hormone.”
    Acromegaly occurs when the body produces too much growth hormone.
    Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone.Damage to or removal of the pancreas
Pancreatitis, pancreatic cancer, and trauma can all harm the beta cells or make them less able to produce insulin, resulting in diabetes. If the damaged pancreas is removed, diabetes will occur due to the loss of the beta cells.
Medicines
Sometimes certain medicines can harm beta cells or disrupt the way insulin works. These include
niacin, a type of vitamin B3
    certain types of diuretics, also called water pills
    anti-seizure drugs
    psychiatric drugs
    drugs to treat human immunodeficiency virus (HIV)
    pentamidine, a drug used to treat a type of pneumonia
    glucocorticoids—medicines used to treat inflammatory illnesses such as rheumatoid arthritis, asthma, lupus, and ulcerative colitis
    anti-rejection medicines, used to help stop the body from rejecting a transplanted organStatins, which are medicines to reduce LDL (“bad”) cholesterol levels, can slightly increase the chance that you’ll develop diabetes. However, statins help protect you from heart disease and stroke. For this reason, the strong benefits of taking statins outweigh the small chance that you could develop diabetes.
If you take any of these medicines and are concerned about their side effects, talk with your doctor.        Last Reviewed November 2016
Sharethis page

Print
    Facebook
    X
    Email
    
    More Options
    
    WhatsApp
    LinkedIn
    Reddit
    Pinterest
    
    Copy Link
                *Previous:*
                What Is Diabetes?
            *Next:*
                Risk Factors for Type 2 Diabetes

                This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases
(NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts. Contact Us
**Hours:** 8:30 a.m. to 5 p.m. ET, Monday - Friday**Email:** healthinfo@niddk.nih.gov**Phone:** +1-800-860-8747**TTY:** +711
Chat
Live Chat Available8:30 a.m - 5 p.m. ETMonday - Friday
Follow Us
LinkedIn
X
Facebook
YouTube
InstagramNIH... Turning Discovery Into Health ®
Privacy Policy
    Freedom of Information Act
    Accessibility
    Disclaimers
    Copyright
    Vulnerability Disclosure Policy
Site Map
    For Staff Only
    Get Email Updates
U.S. Department of Health and Human Services
    National Institutes of Health