JET INJECTION OF INSULIN

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Non-mydriatic retinal cameras can take ’Polaroid’ photographs of 45° field retina, including macula and optic disc, without the need to dilate the pupils. We have assessed the potential of the Canon series of these cameras as screening tools in busy diabetic clinics.4,5The detection rate of the camera in 227 eyes was compared with that achieved by a group of 15 clinic doctors using ophthalmoscopy. Ophthalmoscopy through undilated and dilated pupils missed 76% and 56%, respectively, of instances of diabetic retinopathy detected by the camera. The improved detection rate with the camera included both background and serious retinopathy. Our experience suggests that the statement of Gatlin and colleagues about ophthalmoscopy through dilated pupils in a darkened room being the best method for screening for diabetic retinopathy may no longer be true and that non-mydriatic retinal photography may be the screening method of choice in future. The feasibility of this method in the UK is to be evaluated in a multicentre trial being set up by the Department of Health and Social Security. R. E. J. RYDER Diabetic Unit, VORA J. University Hospital of Wales, a

.

I

Initial UAE 15 V9/mm or no progression m elevated albumin excretion (namely two patients with albumm excretion rate at 15.9 and 23.3 jjg/mtn who did not increase m

albumin excretion at

. Initial UAE z 15

follow-up)

jig/min and increasing albumin excretion

Follow-up fundoscopy plotted against initial fundoscopy in patients with insulin-dependent diabetes (1004 year follow-up). and examination of lower extremities, and metabolic control via haemoglobin Alc assays and multiple evaluations of blood glucose. Patients should be examined early in the course of diabetes and after 6-8 years. If no signs of complications are present assessment of complications should be done again after 2-3 years. If signs of complications are present, especially microalbuminuria, patients should be followed more intensively both for vascular complications, for improved metabolic control, and for antihypertensive treatment when necessary.

(biothesiometer)

Second University Clinic of Internal Medicine,

Department of Ophthalmology, Kommunehospitalet, and

DK-8000 Aarhus C, Denmark 1 2

C. E. MOGENSEN J. VIGSTRUP N. EHLERS

Barnett AH, Dallinger K, Jennings P, Fletcher J, Odugbesan O Microalbuminuria and diabetic retinopathy Lancet 1985, i: 53-54. Mogensen CE Progression of nephropathy in long-term diabetics with proteinuria and effect of initial antihypertensive treatment Scand J Clim Lab Invest 1976, 36: 383-88

3 4

5

6 7 8

Mogensen CE, Christensen CK Predicting diabetic nephropathy in insulin-dependent patients N Engl J Med 1984, 311: 89-93 Parving H-H, Oxenboll B, Svendsen PAa, et al. Early detection of patients at risk of developing diabetic nephropathy a longitudinal study of urinary albumin excretion Acta Endocrinol (Copenh) 1982, 100: 500-55. Viberti GC, Jarrett RJ, Mahmud U, et al. Microalbuminuria as a predictor of clinical: nephropathy in insulin-dependent diabetes mellitus. Lancet 1982, i: 1430-32. Mogensen CE Microalbuminuria and incipient diabetic nephropathy Diabetic Nepluopathy 1984; 3/4: 75-78 Mogensen CE Microalbuminuria predicts clinical proteinuria and early mortality in maturity-onset diabetes N Engl J Med 1984, 310: 356-60. Jarrett RJ, Viberti GC, Argyropoulos A, et al Microalbuminuria predicts mortality in non-insulin-dependent diabetes Diab Med 1981; 1: 17-19

1. Sussman EJ, Tsiaras WG, Soper KA. Diagnosis of diabetic eye disease. JAMA 1982; 247: 3231-34. 2. Foulds WS, MacCuish A, Barrie T, et al. Diabetic retinopathy in the west of Scotland: Its detection and prevalence and the cost effectiveness of a proposed screening programme. Hlth Bull 1983; 41: 318-26. 3 Spathis GS. Report on diabetic clinics and services (1983). Available from the British Diabetic Association, 10 Queen Anne Street, London Wl. 4. Ryder REJ, Young S, Hayes TM, Owens DR. The Canon CR2-45NM retinal camera markedly improves the detection of diabetic retinopathy through undilated pupils. Diabetologia 1984; 25: 362A. 5. Ryder REJ, Young S, Hayes TM, Vora J, Atiea J, Owens DR. The Canon CR3-45NM polaroid, non-mydriatic camera-a further improvement in the screening for diabetic retinopathy (abstract). Diabetic Med (in press).

JET INJECTION OF INSULIN SIR,-There is good experimental evidence to justify your reservations about the jet injection of insulin (May 18, p 1140). The release of insulin from the site of injection is determined by blood flow and the rate of diffusion in the tissues. In the absence of evidence to the contrary, there is no compelling reason to believe that the jet injector should increase either of these rate-controlling factors. Your editorial fails to take account of the fact that not all of the volume of insulin ejected by jet injectors penetrates the skin. The delivered dose is a complex function of nozzle diameter, distance between nozzle and skin surface and volume ejected from nozzle.’ We showed that at a volume setting ofO-1ml only about 50% of the dose penetrated the skin. At higher dose settings the fraction of the dose penetrating was larger and the variation was less than 12%. At 0 - 05 ml, between 0% and 25% of the ejected volume entered the skin when a small-diameter nozzle was used. A jet injector used to deliver small volumes is thus both more variable and less accurate than a needle and syringe and it consistently delivers less than the stated dose. Uncontrolled changes in insulin dosage are undesirable and in the absence of evidence of greater availability or increased rate of clearance from connective tissue, we agree that jet injectors cannot be recommended. Free Hospital, London NW3 2QG

Royal

SIR,-Responding to Dr Barnett and colleagues’suggestion (Jan 5, 53) that routine screening for microalbuminuria be used to detect diabetics requiring strict ophthalmological follow-up because of a high risk of diabetic retinopathy, Dr Gatlin and colleagues (April p

13, p 875) argue that the

for such screening is weak since, to their 40% of according figures, patients with a treatable blinding condition will be missed. They state that the best method for identifying diabetics with retinopathy is ophthalmoscopy in a darkened room after dilatation of the pupils. Unfortunately, even under such ideal conditions, up to 49% of serious retinopathy may be missed by the physicians who care for most diabetic Such failures reflect defects in ophthalmoscopic screening in practice-ie, in busy clinics where time is scarce and routine pupil dilatation is often impracticable. 48% of diabetic clinics in the UK do not have a dark room.3

T. M. HAYES

Heath Park, Cardiff CF4 4XW

1.

P. M. GAYLARDE I. SARKANY

Gaylarde PM, MacMillan AL, Sarkany I. Penetration and dose of injections with the Porton jet injector. Br J Dermatol 1972; 86: 83-86 THE PREGNANT DIABETIC

case

patients.l,2

StR.—Dr Sutherland and colleagues (June 1,p 1279) refer to J. B. O’Sullivan’s work on the follow-up of gestational diabetes (actually impaired glucose tolerance discovered during pregnancy, according to the WHO definition) implying that these findings provide an additional reason for blood glucose screening during pregnancy. O’Sullivan found that the subsequent incidence of diabetes was greatly increased in women who had impaired glucose tolerance during pregnancy, but this is only a special case of the general observation that men or women (pregnant or not) with impaired glucose tolerance are at special risk of diabetes. Unfortunately, we