Relevance of colour vision and diabetic retinopathy to self-monitoring of blood glucose

Home blood glucose monitoring--the key to good control

Home blood glucose monitoring is one of the corner-stones in the management of type I diabetes. This paper summarizes the aims and effects of this method and will discuss the pros and cons with simple patient-adapted meters and visual judgement of the blood glucose strip. It is underlined that a thorough handling of the strip is essential for the result whatever method used. The problem solving capacity of home blood glucose monitoring in unstable diabetes is illustrated.

Home monitoring of blood glucose and insulin therapy without a photometer

The BM-Test-Glycemie 1-44 test strip facilitates self-monitoring without the use of a photometer. In a population of 33 diabetic patients (age 24.8 +/- 2.9 years) 94% took part in home monitoring for 6-10 months. Of 29 who answered a questionnaire 25 preferred blood glucose testing to urine testing. In a "beta-cell school" it was taught that it is rational if home monitoring of blood glucose is combined with a tailored insulin treatment consisting of long-acting insulin (Ultralente) as a basal insulin and regular insulin (Actrapid) as a meal insulin. In a group of 24 labile diabetic patients 17 preferred this regime compared to earlier use of intermediate acting insulin and regular insulin. Six of these preferred the regular insulin to be taken in three doses. Hypoglycemia, when it occurred, was less distressing in symptoms than previously. Among patients with recent onset of diabetes active participation with dose reduction was seen during the honey-moon stage. The regime is logical and generative, offers a basis for an individualized therapy and a high remission frequency may be expected.

Colour vision deficiency in the medical profession

Colour is often used as a sign in medicine, yet there have been few studies into the effects of a colour vision deficiency (CVD) on doctors' medical skills. Using a literature search, the results indicate the prevalence of CVD in the medical profession and its effects on medical skills. For the congenital form among male doctors in the United Kingdom, the prevalence is shown to be probably about the same as for the population at large; i.e. 8%. However, the data is insufficient for any estimate to be made of the small number of female doctors and for the acquired forms of CVD. The effect on skills is also shown. Because of certain features of their work, general practitioners may have special problems. Thus, it is concluded that medical students and doctors should be screened for the deficiency and advised about it, and that there should be more study of the effects of CVD on decision-making in general practice and some specialties.

Seeing beyond retinopathy in diabetes: electrophysiological and psychophysical abnormalities and alterations in vision

Contrast sensitivity testing, in common with color vision (another test of psychophysical function), demonstrates significant changes in diabetic subjects compared with nondiabetic controls, and there is some evidence for a relationship with grade of retinopathy. Changes in contrast sensitivity have been demonstrated in children and adults with diabetes of short duration, and some evidence exists for a correlation with poor glycemic control, although prospective studies are required to assess this relationship over a longer time period. Although both color vision and contrast sensitivity demonstrate similar patterns, studies that directly compare the two tests suggest that measurement of contrast sensitivity is the more sensitive and specific.

Blue-yellow vision deficits in patients with diabetes

Home blood glucose monitoring has been introduced as a means to achieve good control in patients with diabetes mellitus. Many patients use color-reagent strips and color comparisons to determine blood glucose levels. Intact color vision in the blue-yellow range is necessary for accurately interpreting these strips.Blue-yellow vision deficits occur as a consequence of eye disease and are not genetic or sex-linked. We evaluated blue-yellow vision acuity in 70 diabetic patients and in 19 age-matched control subjects. The patients with diabetes were subdivided according to their degree of retinopathy as follows: no disease (N = 14), nonproliferative diabetic retinopathy (N = 16), proliferative diabetic retinopathy (N = 14) and postlaser-treated (N = 26). None of the control group had deficits. Each group of diabetic patients had a statistically significant increase in color vision deficits compared with the controls. In the laser-treated group, deficits occurred in most patients, were more severe and were significantly increased over all other diabetic subgroups. These deficits may impair visual interpretation of home blood glucose monitoring strips.