Type 1 diabetes is sometimes called insulin-dependent, immune-mediated or juvenile-onset diabetes. It is caused by an auto-immune reaction, where the body's defence system attacks the insulin-producing cells. The beta cells of the pancreas therefore produce little or no insulin, the hormone that allows glucose to enter body cells. The reason why this occurs is not fully understood. The disease can affect people of any age, but usually occurs in children or young adults. People with this form of diabetes need injections of insulin every day in order to control the levels of glucose in their blood. Without insulin, people with type 1 diabetes will die.
Symptoms
The onset of type 1 diabetes is often sudden and dramatic and can include symptoms such as:
- abnormal thirst and a dry mouth
- frequent urination
- extreme tiredness/lack of energy
- constant hunger
- sudden weight loss
- slow-healing wounds
- recurrent infections
- blurred vision
Potential risk factors
Studies now show that while incidence is on the increase among children, indicating a shift to a younger age at onset. The causes of the changes over time are unknown and although migration might slowly change the genetic background within a population, the rapid changes in incidence rate reported to occur within comparatively short time spans are more likely to be due to changes in environmental risk factors. These environmental risk factors may initiate autoimmunity or accelerate and precipitate an already ongoing beta cell destruction 1 . These risk factors include:
Early events
Potential risk factors which may initiate the autoimmune process include early fetal events e.g. blood group incompatibility; maternal viral infections during pregnancy; and early exposure to cow's milk components and other nutritional factors.
Population-based case-control studies have identified some protective factors, including a long duration of breast feeding 2 , early vitamin D supplementation 3 , pre-school day care (as a proxy measure of infections) 4 and atopic diseases 5 .
Lifestyle
Since type 1 diabetes in childhood is associated with estimates of general wealth such as Gross Domestic Product(GDP), it has been suggested that lifestyle habits related to welfare might be responsible for the changes in trend. Wealth is a well-known determinant of birth weight and childhood growth.
Weight and growth
Different estimates of child growth such as high birth weight, an increased height, weight, weight for height and body mass index (BMI) have repeatedly been shown to be risk factors for childhood onset diabetes 6 7 8 9 10 . Rapid growth is associated with high growth hormone levels and an increased number of fat cells both leading to insulin resistance and thereby an overloading of the beta cell. Although autoimmune mechanisms are responsible for the beta cell destruction leading to type 1 diabetes, overload factors may accelerate this process.
1.Dahlquist,G. The Diabetes Annual WHO vol 8..In Diabetes in children: The etiology in an epidemiological perspective..Amsterdam: Elsevier; 1994.p-
2.Akerblom,H.K. Vaarala,O. Hyoty,H. Ilonen,J. Knip,M. Environmental factors in the etiology of type 1 diabetes. Am J Med Genet.2002; 115(1): 18-29
3.EURODIAB Substudy 2 Study Group Vitamin D supplement in early childhood and risk for Type I (insulin-dependent) diabetes mellitus.. Diabetologia.1999; 42(1): 51-54
4.EURODIAB Substudy 2 Study Group Infections and vaccinations as risk factors for childhood type I (insulin-dependent) diabetes mellitus: a multicentre case-control investigation.. Diabetologia.2000; 43(1): 47-53
5.EURODIAB Substudy 2 Study Group Decreased prevalence of atopic diseases in children with diabetes.. J Pediatr.2000; 137(4): 470-474
6.Blom,L. Persson,L.A. Dahlquist,G. A high linear growth is associated with an increased risk of childhood diabetes mellitus. Diabetologia.1992; 35(6): 528-533
7.Dahlquist,G. Bennich,S.S. Kallen,B. Intrauterine growth pattern and risk of childhood onset insulin dependent (type 1) diabetes: population based case-control study. BMJ.1996; 313(7066): 1174-1177
8.Stene,L.C. Magnus,P. Lie,R.T. Sovik,O. Joner,G. Birth weight and childhood onset type 1 diabetes: population based cohort study. BMJ.2001; 322(7291): 889-892
9.Hypponen,E. Virtanen,S.M. Kenward,M.G. Knip,M. Akerblom,H.K. Obesity, increased linear growth, and risk of type 1 diabetes in children. Diabetes Care.2000; 23(12): 1755-1760
10.EURODIAB Substudy 2 Study Group Rapid early growth is associated with increased risk of childhood type 1 diabetes in various European populations. Diabetes Care.2002; 25(10): 1755-1760
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