Aust. N.Z. J. Med. (1977), 7, pp. 161-162

cnsE

REPORT

Insulin Aggravated Postural Hypotension Karen T. Palmer", Christine J. Perkinst and R. 6. W. Smith*

From Wellington Hospital, Wellington, New Zealand

Summary: Insulin aggravated postural hypotension. Karen T. Palmer, Christine J. Perkins and R. B. W. Smith, Aust. N.Z. J. Med., 1977, 7. pp.161162.

In a 76-year-old diabetic with symptomatic postural h ypotension during the mornings, this was greatly improved by changing his time of insulin administration from 7.30 a.m. to 11.30 a.m.

Postural hypotension is a common disorder in elderly persons.'. It may be induced by diuretics, by depletion of the extra-cellular fluid volume3, or by psychotherapeutic and other drugs which interfere with the reflexes controlling blood p r e ~ s u r e Recently, .~ insulin has been reported to provoke postural hypotension in diabetics with autonomic n e ~ r o p a t h y . ~ In persons in whom postural hypotension is aggravated by insulin, the problem is difficult to avoid. We present here the case of an elderly man, in whom this problem was overcome by changing the time of insulin administration.

hydration with oral fluid and increased dosage of insulin, he still had a postural drop of blood pressure from 160/90 mmHg lying to 120170 mmHg standing, with a supine heart rate of 58/minute. He had absent ankle jerks, absent vibration sense at the knees and ankles, bilateral cataracts, no evidence of diabetic retinopathy, small pupils which responded sluggishly to light, and fat atrophy on both upper arms where he had received nearly all of his insulin injections. Even in a very warm room there was no sweating. He denied any problems with micturition or bowel function, but had been impotent for several years. He had normal haematological findings (Hb 129 g/l, PCV .357), urea and electrolytes (urea 8 .5 mmol/l, creatinine 0.11 mmol/l, Na 139 mmol/l, K 4 . 2 mmol/l, C1 100 mmol/l, bicarbonate 26 mmol/l). WR and VDRL were negative, and tests of thyroid function were normal. On deep breathing at six breaths/minute, his heart rate varied from 58-60/minute on analysis of individual R-R intervals on an ECG.6 In the sitting position, his heart rate was 60-62/minute. During Valsalva's manoeuvre', his heart rate initially fell to 58/minute, and then rose to 65/minute. There was no reflex bradycardia on ceasing the manoeuvre -the rate remained at 65.

Case Report

In February 1976, a 76-year-old male retired mathematics teacher was admitted io hospital because he had become very faint, and was unable to stand by himself. Diabetes had been diagnosed in June 1960, and he was treated with diet and tolbutamide. Over the years control was variable and, in 1972, metformin was added to his treatmbmt. In April 1975, he was admitted to hospital with keto-acidosis following his failure to take medications. Therapy was changed to insulin lente once daily, and immediately thereafter the patient began to experience faintness during the mornings. Following discharge from hospital a district nurse attended him each morning to administer the insulin. Because of faintness during the mornings, he remained in bed until mid-day. A postural drop in blood pressure was recorded for the first timewhen he was admitted with faintness in February 1976. When his initial condition was improved by re*Physician.

' ?Medical Registrar. Correspondence: Dr. R. B. W. Smith, Department of Medicine, Wellington Clinical School, Wellington Hospital, Wellington 2, New Zealand Accepted for publication: 1 November, 1976

FIGURE 1 . Standing blood pressure during the days when insulin was given at 7.30 a.m. )-( and 11.30 a.m. (-x-). Each curve is a mean of seven days' recordings. The differences are significant at 9 a.m. (meankSEM 1 1 8 + 5 and 9 9 + 3 , t = 3.1, P i 0.02). and 1 0 a.m. ( 1 2 0 + 8 and 9 6 + 4 , t = 2.6, P < 0.05). but not at other times.

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Blood pressure recordings on many days showed early morning levels, after standing for one minute, of about 110170 mmHg and, following the injection of insulin at 7.30 a.m. (Lente 38 units and Semi-lente 8 units), the standing blood pressures fell about 30 mmHg, and the effect persisted about six hours (Fig. 1). When insulin was delayed, there was no fall in standing blood pressure during the morning, and his alertness during the morning was immediately improved. When insulin was injected at 11.30 a.m., there was a drop of about 10 mmHg in the standing blood pressure, and there was no impairment of general alertness. During several days of insulin injections at 11.30 a.m. he remained alert during the morning and did not remain in bed. When the injection time was changed back to 7.30 a.m. there was an immediate onset of a wish to stay in bed, and his blood pressures were again lower. After several days he was again changed to 11.30 a.m. injections, and improvement in general alertness and enthusiasm was immediately apparent, and this has persisted. His blood pressure readings have remained above 130/ 80 mmHg standing and lSOj80 mmHg lying. Discussion

This diabetic 76-year-old man had autonomic neuropathy with postural hypotension being the main clinical manifestation. The small degree of heart rate variation on deep breathing is evidence for vagal neuropathy.6 Postural hypotension tends to be ,worse during the mornings. This is usually attributed to a diurnal variation in extra-cellular fluid volume, 'being lowest on first rising.8 It is usually seen in persons with postural hypotension that symptoms tend to improve during the day-presumably due to expansion of the extra-cellular fluid volume, and one of the more successful therapies for postural hypotension is salt-retaining steroids.' Page and Watkins showed that insulin may provoke postural hyDotension in diabetics with autonomic n e ~ r o p a h y .In~ patients on twicedaily soluble insulin, there was a fall in standing blood pressure from one to six hours after both

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the morning and evening subcutaneous injections, and the effect was apparent within about five minutes of an intravenous injection. The effect does not depend upon hypoglycaemia, and occurs even when blood sugar levels were abnormally high. In diabetics without neuropathy, insulin causes no significant postural fall in blood pressure, but there is a significant rise in heart rate." This is believed to be a compensatory mechanism. It is thought likely that insulin produces a reduction in vasomotor There is, thus, good reason for not giving insulin at a time when the postural hypotension is most marked. The change to 11.30 a.m. was followed immediately by the patient being more sprightly during the mornings, and this clinical improvement was accompanied by a lesser degree of postural hypotension. In insulin-dependent diabetics with autonomic neuropathy, postural hypotension during the mornings may be ameliorated by changing the time of insulin administration.

References 1. JOHNSON, R. H., SMITH,A. C., SPALIXNG, I . M. K. and WOLLNWL. (1965): Effect of posture o n blood pressure in elderly patients, Luncet 1, 731 2 . CAIRD,F. I., ANDREWS, G. R.and KENNEDY, R D. (1973): Effect o f posture o n blood pressure in the elderly, Brit. Heart J. 35, 527. 3. W A L K ~ RW. , G. (1966): Indications and contraindications for diuretic therapy, Ann. N . Y . Acad. Sci. 139, 481 4. BARRACLOUGH. M A and S H A R P E \ ~ C H A FE. E RP., (1963): Hypotension from absent circulatory reflexes: Effects of alcohol, barbiturates, psychotherapeutic drugs and other mechanisms. Lancrt I, 1121. 5 . PAGE,M. McB and WATKINS,P. J. (1976). Provocation of postural hypotension by insulin in autonomic neuropathy, D i a b e m 25, 90. 6. WHEELER, T. and WATKINS:P. J. (19731. Cardiac denemation 111 diabetes, Brit. med. J . 4, 584. 7. SHARPEY-SCHAFER, E P. (19551: Effects of Valsalva's manoeuvre o n the normal and failing circulation, Bril. mcd. J. 1, 693. 8. Editorial (1973): Postural hypotension in the elderly, Bril. med. J. 4, 246. 9. BANNISTER, R. G., ARDILL,L. and FENTEM. P. (1969): An assessment of various methods of treatment of idiopathic orthostatic hypotension, Quart. J . Med. (N.S.) 38, 377. 10. PAGE,M. McB., SMITH,R. B. W. and WATKINS, P. J. (1976): Cardiovascular effects of insulin, Brit med. J . 1 , 430.

Insulin aggravated postural hypotension.

Aust. N.Z. J. Med. (1977), 7, pp. 161-162 cnsE REPORT Insulin Aggravated Postural Hypotension Karen T. Palmer", Christine J. Perkinst and R. 6. W...
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