Diabetes

Back in 1969, the BMJ published the first report of a possible link between enteroviruses and type 1 diabetes (BMJ 1969;3:627, www.bmj.com/content/3/5671/627). It’s good to be able to look back at the full text of that report on bmj.com in light of the systematic review on the same topic published in this week’s journal. The earlier authors looked at viral antibody titres in 528 people and found that patients with recent onset of insulin dependent diabetes had higher antibody titres to coxsackie B virus than those without diabetes or those with diabetes of longer duration.

In their systematic review, Wing-Chi Yeung and colleagues have tested this apparent association across the accumulated evidence of 40 years (doi:10.1136/bmj.d35). They identified 33 case-control studies in a total of 4448 people. Their meta-analysis showed a significant association between a positive test for enterovirus RNA or viral capsid protein and having type 1 diabetes or related autoantibodies. All the usual caveats apply, given that these were case-control studies and used heterogeneous methodologies, and the authors make clear that they can’t determine a causal relation. But the association is strong statistically, and, as Didier Hober and Famara Sane point out in their editorial (doi:10.1136/bmj.c7072), it fits with most of the epidemiological studies on this topic.

Could this hold out new hope for prevention and treatment of type 1 diabetes? Hober and Sane are optimistic, though they stress that the mechanism has yet to be explained. It seems likely, they say, to involve an interplay between viruses, pancreatic cells, the immune system, and a person’s genotype.

While awaiting further advances, children continue to develop type 1 diabetes. Keya Ali and colleagues tell us that the incidence in northern Europe is increasing by about 4% a year, making it one of the commoner long term conditions of childhood (doi:10.1136/bmj.d294). Yet the diagnosis is often delayed: one study found that about a third of children with newly diagnosed diabetes had at least one related medical visit before the diagnosis was made. Drinking and frequent micturation can be misinterpreted by school and parents, and doctors may not ask about these things when a child presents with other non-specific symptoms. The importance of doing so is clear when we learn that children can develop dehydration and acidosis within 24 hours of the first presentation.

For patients with established type 1 diabetes, a cure remains elusive. Back in 2001, a BMJ clinical review hailed islet transplantation as the likely future treatment of choice. But this week’s clinical review is more circumspect. Islet transplantation is an option, say Hanneke de Kort and colleagues (doi:10.1136/bmj.d217), but currently only for those patients whose blood sugars are highly labile and who have recurrent hypoglycaemia and poor hypoglycaemia awareness. Patients need to take lifelong immunosuppressive treatment, and most will need insulin again within five years. So not yet the cure patients are hoping for.

Of course, type 1 diabetes is but a small part of the overall burden of diabetes on health systems. The second article in our new therapeutics series looks at glucagon-like peptide-1 analogues as alternatives to insulin for third line treatment of type 2 diabetes (doi:10.1136/bmj.d410), and our 10 minute consultation describes how to manage a patient presenting with increasingly frequent episodes of hypoglycaemia (doi:10.1136/bmj.d567).