Ocular complications of diabetes mellitus.

A GENERAL review of the more important aspects of diabetes mellitus is desirable before proceeding to a consideration of the particular problem of the ocular complications. Diabetes mellitus, already a common disease, is likely to become more common in the future. It has been estimated that in the United States of America there are about 1 million diabetics and probably another million undiscovered, and in the United Kingdom the number has been variously estimated at different times from 33,000 (Stocks, 1949) to 200,000 (Joslin, and others 1946). In Cardiff there are two diabetic clinics, one at the Royal Infirmary, and the other at the City Council Health Centre. Approximately 1,200 attend these clinics, and of these, six hundred reside within the boundaries of the city, which, with an estimated population of 250,000, gives an incidence of 240 cases of diabetes per 100,000 of population, this figure being comparable with that obtainable in other parts of the country. No fewer than 268 new patients were seen during 1952, and approximately six to eight new patients seek advice each week. These figures refer only to those attending the clinics, and there must be many others who do not attend or who are as yet undiscovered. The disease is becoming more common for a variety of reasons. Firstly, it is a hereditary disease and is transmitted as a Mendelian recessive. Secondly, since the discovery of insulin, there has been an increase in the fertility of diabetics, a reduction in the incidence of maternal mortality, and an improvement in the foetal survival rate. It has been estimated, for example, that for every 282 pregnancies, there is one diabetic pregnancy, whilst the maternal mortality has been reduced to between 2 and 9 per cent. (Gilbert and Dunlop, 1949). Thirdly, diabetics are living longer and, if properly controlled, may live almost as long as non-diabetics. This is mainly due to insulin therapy, but improved dietary control and the advent of chemotherapy, antibiotics, and anticoagulants play an important part. It has been estimated that a child developing diabetes mellitus at age 10 had an expectation of life of 2.6 years in 1922 as compared with one of 39.8 years in 1938; comparable figures for a young adult are 6.3 years in 1922 and 27.6 years in 1938.