Arrhythmias and Coronary Heart Disease

Occasional cardiac arrhythmias have been demonstrated in normal subjects during experimental hypoglycaemia studies. It would now be considered unethical to perform hypogly-caemia studies in patients with known heart disease, but many studies were performed in an earlier era both in diabetic and non-diabetic patients with coronary heart disease to examine the effects of acute hypoglycaemia (Fisher and Frier, 1993). Sinus bradycardia has been reported in a very small number of cases (Pollock et...

Metabolic Changes During Pregnancy

Fundamental changes occur in maternal metabolism and physiology during pregnancy. Over 280 days the mother's weight increases on average by 12.5 kg. The main increase in weight occurs in the second half of pregnancy and is caused by the growth of the conceptus, the enlargement of maternal organs, maternal storage of fat and protein and an increase in maternal blood volume and interstitial fluid. An increase in the basal metabolic rate results in the need for increased energy intake. In addition...

Structural Changes of the Brain in Diabetes

Hypertension and hyperlipidaemia are common in diabetes and cerebrovascular disease is a recognised macrovascular complication. Atheromatous cerebral artery occlusion involving major vessels, embolism from cervical arteries, and lacunar strokes are more extensive and occur at an earlier age in diabetic patients compared with the non-diabetic population (McCall, 1992 Mankovsky and Ziegler, 2004). It is uncertain whether microvascular disease affects the brain. Following the death of a group of...

Organisation of Clinical Care

Kitzmiller Baby Ultrasound

In many centres clinical care is delivered by a multidisciplinary combined obstetric diabetic team with very regular out-patient reviews to assess metabolic control and obstetric progress Figure 10.1 . Home blood glucose monitoring results are assessed and insulin regimen and dietary intake modified to optimise glycaemic control and HbA1c Figure 10.2 . Most women present for booking at around eight weeks gestation when an early scan will provide an accurate estimate of gestational age. This is...

Employment

The risk of developing acute hypoglycaemia and its consequences mainly in people with insulin-treated diabetes provide reasons why some forms of employment are not available to individuals who require insulin therapy. Employment prospects are often restricted where the threat of hypoglycaemia poses a risk to the diabetic worker or to his or her colleagues, and to the general public. With some occupations, such as a train or bus driver, or a commercial airline pilot, any risk of hypoglycaemia is...

Counterregulation During Hypoglycaemia

The potentially serious effects of hypoglycaemia on cerebral function mean that not only are stable blood glucose concentrations maintained under physiological conditions, but also if hypoglycaemia occurs, mechanisms have developed to combat it. In clinical practice, the principal causes of hypoglycaemia are iatrogenic as side-effects of insulin and sulphony-lureas used to treat diabetes and excessive alcohol consumption. Insulin secreting tumours such as insulinoma are rare. The mechanisms...

The Somogyi Phenomenon The Concept Of Rebound Hyperglycaemia

In the late 1930s, a Hungarian biochemist, Michael Somogyi, working in St Louis, USA, suggested that nocturnal hypoglycaemia might provoke rebound hyperglycaemia on the following morning, and he supported his hypothesis with a demonstration that reducing evening doses of insulin led to a reduction in fasting urinary glycosuria Somogyi, 1959 . He proposed that nocturnal hypoglycaemia provokes a counterregulatory response with rises in plasma epinephrine, cortisol and growth hormone resulting in...

Factors Predisposing Patients to Severe Hypoglycaemia in Intensified Insulin Therapy

The relationship between impaired symptomatic awareness of hypoglycaemia and an increased rate of severe hypoglycaemia is well established Hepburn et al., 1990 Gold et al., 1994 Clarke et al., 1995 , although affected patients in these studies were not subject to strict glycaemic control. The association between counterregulatory failure and increased risk of severe hypoglycaemia is also well recognised Ryder et al., 1990 . Indeed, counterregulatory failure was proposed as a predictor of risk...

Effect of Hypoglycaemia on Cerebral Blood Flow and Structure

Cerebral Blood Flow And Age

Hypoglycaemia promotes a redistribution of regional cerebral blood flow Tallroth et al., 1992 MacLeod et al., 1994 Kennan et al., 2005 which may encourage localised neuronal ischaemia, particularly if the cerebral macro- or microcirculation is already compromised in subjects with type 1 diabetes. Using techniques such as Single Photon Emission Tomography, the blood flow to the frontal lobes has been shown to be increased during acute hypoglycaemia in non-diabetic subjects Tallroth et al., 1992...

Activation of the Autonomic Nervous System

The autonomic nervous system comprises sympathetic and parasympathetic components Figure 1.5 . Fibres from the sympathetic division leave the spinal cord with the ventral roots from the first thoracic to the third or fourth lumbar nerves to synapse in the sympathetic chain or visceral ganglia, and the long postganglionic fibres are incorporated in somatic nerves. The parasympathetic pathways originate in the nuclei of cranial nerves III, VII, IX and X, and travel with the vagus nerve. A second...

Human Insulin

For 60 years after its discovery, insulin for therapeutic use was obtained from the pancreata of cattle and pigs. With the development of recombinant DNA technology it was possible to 'genetically engineer' molecules and insulin was the first protein to be made in this way, becoming available for the treatment of humans in the 1980s. Several of the existing animal insulin formulations were withdrawn, principally for commercial reasons, and human insulin rapidly became the most commonly...

Classifying Symptoms of Hypoglycaemia

Until now the symptoms of hypoglycaemia have been treated as a homogeneous whole. Can these symptoms be divided into different groups Hypoglycaemia has effects on more than one part of the body, and the symptoms of hypoglycaemia reflect this. First, the direct effects of a low blood glucose concentration on the brain - especially the cerebral cortex - cause neuroglycopenic symptoms. Second, autonomic symptoms result from activation of parts of the autonomic nervous system. Finally, there may be...