The probability of binding (chelation) between zinc and organic compounds-that is, compounds containing carbon, nitrogen and oxygen-is high. Such binding usually occurs between the negative-ion- rich centres of either the oxygen or nitrogen groups of the chemical and the positively charged zinc (Zn2+) ion. In the case of insulin-zinc complexes found naturally in the pancreas, the binding is reversible, as it enables insulin to be stored until required.

Whatever the route of destruction of the pancreas' ability to secrete insulin, it is worthwhile noting that some of the drugs that diabetic children are exposed to during fetal development are structurally similar to each other. For example, in the survey of diabetic children that I carried out, one child was exposed to Asacol (mesalamine) and another to paracetamol. The structure of Asacol is similar to para-aminophenol, a highly toxic chemical formed in the body in tiny quantities following paracetamol (acetamino-phen) breakdown. What's more, Asacol and penicillamine both have an amine (NH2) and a carboxyl (COOH) group.

A drug connection would also account for another mysterious feature of diabetes: that only the beta cells of the pancreas are destroyed. The alpha and delta cells of the pancreas, also located in the islets of Langerhans where the beta cells are, are not damaged in diabetes. It is only the zinc-containing beta cells that are damaged. This selective destruction may well be caused by chemicals with an affinity for zinc.

UK dispensing practices
When considering diabetic children in the same family, rather than heredity, the cause may be the family doctor.

If the family's physician commonly prescribes antibiotics to babies and children, and if one accepts that antibiotics may be implicated in the onset of diabetes, then it would not be surprising to find more than one diabetic child in the same family.

The table shown in the box on page 7 shows the geographical variation in the incidence of diabetes in England among the under-15-year-old age group. East Anglia, a predominantly rural area, has the highest incidence, whereas the four Thames regions, areas of higher population density and pollution, have the lowest. The incidence in East Anglia is more than double that of the North West Thames region.

This pattern of a rural area having a higher incidence of diabetes than an urban region is also seen in Scotland. In the UK, doctors are allowed to dispense their own drugs for patients who are living more than a mile away from the closest pharmacy. Consequently, although few GPs in builtup areas dispense their own drugs, in rural areas, the proportion of dispensing practices can be rather high.

In one study comparing children living in the Cambridgeshire and Wessex Areas, the health authorities' data showed that a high proportion of diabetic children lived in the countryside and not in the towns, despite the presumably higher population density of children in the latter.

In other words, if all children were at equal risk of diabetes irrespective of where they lived, the expectation would be to find more diabetic children in the urban areas.

Furthermore, it appears that some of the dispensing practices in the countryside were considerably more affluent-despite being supported by fewer GPs-compared with those in the outer-London areas. Indeed, some surgeries had recently been purpose-built, and at considerable cost. It was also noticeable that in some of these practices, antibiotics were apparently being liberally prescribed to babies and children. The small areas looked at were located in area health authorities with a high incidence of diabetes.