History and exam

Key diagnostic factors

Geography is a strong risk factor.

Getting up at night to urinate is typical.

Getting up at night to drink water is typical.

Other diagnostic factors

Usually presents in childhood or adolescence. Typical age 5 to 15 years.

Average age varies in different studies. Incidence increasing in children <5 years old.[36]

Weight loss occurs at onset.

Occurs with high or fluctuating blood sugar levels.

Suggest diabetic ketoacidosis.

Suggests diabetic ketoacidosis.

Suggests diabetic ketoacidosis.

Suggests diabetic ketoacidosis.

Suggests diabetic ketoacidosis.

Risk factors

Human leukocyte antigen (HLA) risk profile for type 1 diabetes is widening over time, which may reflect increased environmental influence on susceptible genotypes.[32]

Geographical variation ranges from 1/100,000 in regions of China to 38/100,000 in Finland.[7] Regional variation suggests different contributing risk exposures.[10]

In one study, concordance for type 1 diabetes was 27.3% in monozygotic twins and 3.8% in dizygotic twins.[30]

HLA on chromosome 6 thought to contribute to half of the familial basis.[31]

DR4-DQ8 and DR3-DQ2 present in 90% of children with type 1 diabetes; considered susceptibility genes.[31]

DR15-DQ6 considered protective.[31]

Insulin gene on chromosome 11 thought to be second most important susceptibility gene, contributing 10% of genetic susceptibility.[31]

Several other loci associated with type 1 diabetes under study.[31]

Strongest evidence to date is for human enteroviruses.[15][16][17]

Among dietary factors, supplementation with vitamin D may be protective.[18][19] 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.[20][21][22] There is no consensus about the effect of breastfeeding on risk for type 1 diabetes.[33]

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