What Are the Symptoms of Type 1 Diabetes?

June 28th 2019
Sara Hunt, MSN, RN, PHN, FNP-C
Sara Hunt, MSN, RN, PHN, FNP-C

It is important to recognize the signs of this disease, which can cause many complications and a decrease in life expectancy.

Type 1 diabetes (T1D), also known as brittle diabetes, insulin-dependent diabetes mellitus, juvenile diabetes, labile diabetes, and sugar diabetes,1,2is a serious, life-long autoimmune condition that leads to progression of macrovascular and microvascular damage and risk of premature death. People with T1D are at significantly greater risk of developing complications, such as cardiovascular, eye, and kidney disease, as well as lower extremity amputation, and can they expect a decrease in life expectancy. It is estimated that patients with diabetes live for about 12 years less than those who do not have the disease.3

In recent years, there has been a large focus on type 2 diabetes (T2D), and this is for good reason. T2D has reached global pandemic status,4with more than 415 million people affected globally,4and it is estimated that up to 642 million will have T2D by 2040.4Interestingly, it has been reported that there is also a global rise in the number of those with T1D.5One study estimates that T1D has been increasing by about 3% per year over the past few decades,5and some epidemiological and immunological research has drawn links between certain environmental factors and the development of T1D.5

T1D can occur at any time but is more common earlier in life, and typical symptoms of diabetes may not be so obvious in certain populations.

Infants and Toddlers

T1D is quite rare in this population. Less than 1% of children under age 1 and less than 2% of children under age 2 are diagnosed with it.6The peak age of diagnosis does not occur until age 10 to 14.7The presentation and rareness of the condition make it easily misdiagnosed.6The classic symptoms of polydipsia, polyphagia, polyuria, and weight loss may not present obviously.6Unlike adults, infants and very young children cannot verbalize fatigue, hunger, thirst, or other symptoms. Irritability that results from T1D may easily be mistaken for other common causes of irritability in infants and toddlers, and diaper rash may be brushed off because it is so common.6This is also true for excessive urination and frequent feedings. Unfortunately, concerned parents may be dismissed or reassured that nothing is wrong, and a child may be misdiagnosed with a , otitis media, upper respiratory infection, or urinary tract infection.6It may not be until the infant or very young child is in full-blown diabetic ketoacidosis (DKA) that the diabetes is recognized. It is estimated that about 15% to 70% of infants and children who are diagnosed with diabetes in developed countries are already in DKA,7and in the US the number is about 25% of these cases.7The DKA symptoms, such as dehydration, Kussmaul breathing, and obtundation, may raise red flags for other serious conditions, such as asthma, bronchiolitis, meningitis, and septicemia, and at the point of hospitalization the child becomes diagnosed.6The mortality rate of DKA in children is about 0.15% to 0.3%, and the No. 1 cause of death related to DKA is cerebral edema, which kills 20% to 25% of patients.7

Children and Adults

T1D is diagnosed most frequently during childhood, accounting for about 85% of diabetes among those who are younger than 20,7but about one quarter of people with T1DMare diagnosed during adulthood.7It’ is also estimated that about 10% of adults who have been diagnosed with T2D actually have antibodies that are associated with T1D.7Classic symptoms of T1D can develop slowly over time or rapidly8and include polydipsia, polyuria, and weight loss.7,8Rapid onset is more common in children, who may have little to absolute insulin insufficiency.8Slower disease progression is more common with adults, who may maintain some beta cell function for longer periods of time, which often prevents rapid onset of DKA.8One study that evaluated 1260 children under age 15, the 3 most commonly observed symptoms were polyuria (96%), weight loss (61%), and fatigue (52%).7

Emergency Symptoms

The 3 main emergencies associated with diabetes are DKA, hyperglycemic hyperosmolar state (HHS), and hypoglycemia.9DKA is the leading cause of death in children and young adults with T1D, but its overall mortality in the United States is less than 1%/9Although HHS is not as common as DKA, its mortality rate is 10 times higher.9However, HHS is much more common in the elderly with T2D.10Hypoglycemia is the most common adverse effect of diabetes management.9Up to 30 % to 40% of patients with T1D may experience hypoglycemia each year.9

Symptoms of hyperglycemia are coma; confusion; difficulty concentrating; drowsiness; fatigue; feeling unwell; frequent infections, such as cystitis or thrush; muscle weakness; nausea; polydipsia; polyuria; stomach pain; vision changes; and weight loss.11

Symptoms of hypoglycemia are anxiety; cold sweats; confusion; difficulty concentrating; headache; nervousness; pallor; polyphagia; restlessness; shivering, tachycardia; and weakness in the knees.11

Sara Hunt, MSN, RN, PHN, FNP-C, is a licensed and board-certified family nurse practitioner, a public health nurse, an adjunct assistant professor of health policy, and a doctor of nursing practice student at the University of California, San Francisco. She was the spring 2015 health policy fellow at the American Association of Nurse Practitioners’ Government Affairs Office in Washington, DC.


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  2. Brittle diabetes (labile diabetes). Diabetes.co.uk website diabetes.co.uk/brittle-diabetes.html. Accessed April 18, 2019.
  3. Huo L, Harding JL, Peeters A, Shaw JE, Magliano DJ. Life expectancy of type 1 diabetic patients during 1997-2010: a national Australian registry-based cohort study.Diabetologia.2016;59(6):1177-1185. 10.1007/s00125-015-3857-4. doi: 10.1007/s00125-015-3857-4.
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  8. American Diabetes Association. Diagnosis and classification of diabetes mellitus.Diabetes Care. 2009;32 Suppl 1(Suppl 1):S62—S67. doi:10.2337/dc09-S062.
  9. Umpierrez G, Korytkowski M. Diabetic emergencies - ketoacidosis, hyperglycaemic hyperosmolar state and hypoglycaemia.Nat Rev Endocrinol. 2016;12(4):222-232. doi:10.1038/nrendo.2016.15.
  10. Pasquel FJ, Umpierrez GE. Hyperosmolar hyperglycemic state: a historic review of the clinical presentation, diagnosis, and treatment.Diabetes Care. 2014;37(11):3124—3131. doi:10.2337/dc14-0984.
  11. Hyperglycemia and hypoglycemia in type 1 diabetes.Institute for Quality and Efficiency in Health Care (IQWiG). 2007. ncbi.nlm.nih.gov/books/NBK279340/. Accessed April 23, 2019.

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