Exploring the Genetics of Type 1 Diabetes - Genetics an...

Exploring the Genetics of Type 1 Diabetes

Exploring the Genetics of Type 1 Diabetes
July 25, 2008
American Diabetes Association

What is the problem and what is known about it so far?

Type 1 diabetes is a disease of the immune system that leads to destruction of insulin-producing β-cells in the pancreas. Some people with type 1 diabetes lose all β-cell function soon after diagnosis; others retain partial β-cell function for a longer period of time. Keeping even a small amount of β-cell functioning can lower the risk of serious diabetes complications. There is evidence that a newly discovered gene, and particularly one variant of that gene, may be related to the level of β-cell functioning in people with type 1 diabetes.
Why did researchers do this particular study?

The researchers wanted to find out whether the presence of the C1858T variant of the PTPN22 gene influences β-cell functioning and metabolic control of newly diagnosed people with type 1 diabetes.
Who was studied?

The study included 120 people diagnosed with type 1 diabetes in Central Italy.
How was the study done?

All patients were tested for the presence of the gene variant. They were all prescribed intensive insulin therapy and had measurements of fasting C-peptide levels (an indicator of β-cell functioning), A1C, and insulin requirements at diagnosis and every 3 months for a year. The changes in these measurements were analyzed statistically to find out if they were related to the presence of the gene variant in question.
What did the researchers find?

β-cell functioning was lower and A1C levels were significantly higher in patients with the gene variant than in those without it throughout the first year after diagnosis with type 1 diabetes. This was true regardless of patients' age at diagnosis, sex, or genetic risk group for susceptibility to diabetes. Although those with the gene variant had poorer β-cell functioning and metabolic control throughout the study, their disease did not progress any faster over the course of the year than that of patients without the gene variant.
What were the limitations of the study?

It is possible that other factors, such as insulin therapy, may influence the progression of type 1 diabetes after diagnosis. Also, although this study identified links between the gene variant and β-cell functioning and metabolic control, without information about patients' β-cell functioning before diagnosis, it could not explain exactly why the presence of the gene variant makes a difference.
What are the implications of the study?

Retaining even a small degree of β-cell functioning can help patients with type 1 diabetes achieve better metabolic control and avoid progression of complications, especially diabetic eye disease. Future therapies aimed at preserving β-cell functioning should take into account the genetic background of type 1 diabetic patients and especially the presence or absence of this gene variant.