Number of cases per month of Type 1 diabetes (n=226)
Ethnicity and genetics
Ethnicity - incidence per 100,000 in different ethnic groups
US Virgin Islands
Hispanics 7.2
Whites 28.9
Blacks 5.9
Hokkaido 1.7
Aust Euro 13.2
Genetics
If an identical twin has Type 1 diabetes then in 50% of cases the other twin will also develop Type 1 diabetes.
If the twins are not identical then less than 10% chance.
Genetic susceptibility
HLA-DR3 and HLA-DR4 are more likely to develop Type 1 diabetes
HLA-DR2 seems protective
Genetics cannot be specified on classical lines of dominant, recessive or intermediate genes
Risk of Type 1 diabetes in siblings.
4% developed Type 1 diabetes by age 22 years.
12% risk in those with HLA DR3 or DR4
56% with raised Islet Cell Antibodies went on to diabetes.
Use of nicotinamide in children with high levels of circulating ICA.
8 children who were 1 st degree relatives of Type 1 diabetics with ICA levels above 80 units were followed for 5 years. All became diabetic after a mean 17 months.
14 other children who were 1 st degree relatives and had raised ICA were given 150 - 300 mg Nicotinamide and followed for 5 years.
1 became diabetic after 25 months
Has led to a major RCT (report in 2003)
Nicotinamide
DENIS (Deutsche Nicotinamide Intervention Study) showed no difference in randomised trial involving 55 children for 3 years. (Lampeter EF. Klinghammer A. Scherbaum WA. Heinze E. Haastert B. Giani G. Kolb H. The Deutsche Nicotinamide Intervention Study: an attempt to prevent type 1 diabetes. DENIS Group. Diabetes. 1998; 47(6):980-4)
Much larger multi national randomised trial (ENDIT) will report in 2003 (Gale et al)
Cows milk
Incidence of Type 1 diabetes in relation to mean yearly consumption of cows milk
Cows milk
Exclude cows milk from rats diet and the incidence of diabetes falls.
Children with diabetes have been breast fed for a shorter period than controls.
Western Samoan children did not get Type 1 diabetes until they moved to New Zealand
Maternal age
Maternal age
Recent study have suggested Type 1 diabetes in children maybe associated with maternal age
Cumulative risk of developing diabetes in siblings of children with Type 1 diabetes in quintiles (median age range 21 -34 years)
Viruses
Coxsackievirus and cytomegalovirus have both been implicated.
Multiple infections in early infancy seem to be protective
Mortality and Morbidity
Mortality
Mortality in UK patients with Type 1 diabetes
SMR by age and sex for people with Type 1 diabetes
Mortality in Type 1 diabetes over time
Summary of aetiological findings
Type 1 diabetes is increasing
Probably caused by a combination of genetic and environmental influences
Role of cows milk?
Nicotinamide?
Seasonal variation
Diet?
Viruses?
Conclusion
Incomplete information on aetiological factors
A number of possibilities for prevention have been raised but have yet to lead to a worthwhile population approach
Still great potential for preventing increase in developed communities
