In research published in the British journal Nature, experts pointed the finger at variants in two genes, HLA-DQB1 and HLA-DRB1, as boosting the risk of Type 1 diabetes.
The genes are located in a gene-rich cluster on Chromosome 6 that is already implicated in autoimmune diseases, the term for disorders in which the body's tissues are attacked by the immune system.
The genes control rogue proteins that apparently play a role in destroying insulin-producing islet cells in the pancreas and in accelerating the disease.
The research, carried out by the Cambridge Institute for Medical Research in Britain, was based on a genomic comparison among 850 pairs of siblings in Britain and the United States.
The results were compared against 4,000 Britons who had Type 1 diabetes or did not have the disease, and then analysed further against 5,000 individuals enrolled in a separate study being conducted by the Wellcome Trust charity.
Other genes previously linked to diabetes are on Chromosomes 1, 2, 16 and 11, but appear to play different roles in unleashing or amplifying this complex disease.
World Diabetes Day was mandated as a UN-backed event by a United Nations resolution last December.
Diabetes affects 246 million people worldwide and is expected to affect some 380 million by 2025, according to figures on the International Diabetes Federation website.
Wednesday's event focused attention on Type 1 diabetes, which typically occurs in childhood and early adolescence and is associated with genetic predisposition.
Incidence of Type 1 diabetes "is rising alarmingly worldwide, at a rate of three percent a year," the Federation says.
Type 2 diabetes, more common, results mainly from an unhealthy diet and inactivity and is becoming epidemic in scale in many developed or fast-developing countries.
Diabetes is a chronic condition in which the body does not produce enough of the hormone insulin, or cannot make proper use of the insulin it does produce, a condition called insulin resistance.
As a result, there are wild fluctuations of glucose in the blood. This can eventually lead to blindness, heart disease, amputations and kidney failure.
Predicting genetic vulnerability to diabetes could offer huge benefits, doctors believe.
In most cases of Type 1 diabetes, many patients are diagnosed too late to save the so-called beta cells that produce the insulin.
There is no cure yet for the disease, but earlier warning can encourage dietary change and swifter glucose control, thus helping to stave off potentially life-threatening complications.