History and exam
Key diagnostic factors
common
polyuria
Getting up at night to urinate is typical.
polydipsia
Getting up at night to drink water is typical.
diabetic ketoacidosis
Approximately half of young people with type 1 diabetes present with diabetic ketoacidosis (DKA); however, adults appear less frequently with this symptom.[1] The prevalence of DKA at (or near) type 1 diabetes diagnosis has increased in the years 2010 to 2016.[47] Symptoms suggesting DKA include nausea and vomiting, dehydration, abdominal pain, rapid breathing, lethargy, and altered mental status.
Other diagnostic factors
common
young age
Usually presents in childhood or adolescence with the highest incidence observed in children aged 10 to 14 years, but can occur at any age.[18]
weight loss
Weight loss commonly occurs at onset.
blurred vision
Occurs with high or fluctuating blood sugar levels.
nausea and vomiting
Suggest diabetic ketoacidosis.
abdominal pain
Suggests diabetic ketoacidosis.
tachypnea
Suggests diabetic ketoacidosis.
lethargy
Suggests diabetic ketoacidosis.
uncommon
altered mental status
Mental status can range from alert in mild diabetic ketoacidosis (DKA) to coma in severe DKA.[43]
Risk factors
strong
genetic predisposition
Over 50 genetic loci associated with type 1 diabetes risk have been identified.[18][36] Genetic variation in the human leukocyte antigen (HLA) region (involved in the immune response), accounts for a large proportion, with HLA DR4-DQ8 and HLA DR3-DQ2 conferring the highest risk.[18][20]
The risk of type 1 diabetes in children with an affected family member is 5% (compared to a risk of 0.3% in children without an affected family member).[20] In one study, concordance for type 1 diabetes was 27.3% in monozygotic twins and 3.8% in dizygotic twins.[37]
In genetically susceptible individuals, environmental factors may trigger the immune-mediated destruction of pancreatic beta cells.[18]
weak
geographic region
There is significant geographic variation in the incidence of type 1 diabetes, and it is more common in European people and less common in Asian people.[12] Human leukocyte antigen (HLA) risk profile for type 1 diabetes is widening over time, which may reflect increased environmental influence on susceptible genotypes.[38] Regional variation suggests different contributing risk exposures.[18]
dietary factors
Among dietary factors, supplementation with vitamin D may be protective.[24][25] Further research is required to determine the effect of cow's milk, early introduction of cereals, or maternal vitamin D ingestion on type 1 diabetes risk.[26][27][28] There is no consensus about the effect of breast-feeding on risk for type 1 diabetes.[39]
drug-induced
There is a possibility that checkpoint inhibitors used for treating cancer may trigger an autoimmune response causing sudden onset of type 1 diabetes.[1]
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