Section 11 Endocrine
11.1 Diabetes mellitus and hypoglycaemia: an overview
DIABETES MELLITUS
Classification system and diagnostic criteria
The classification system and diagnostic criteria for diabetes were re-examined in 1996 by the American Diabetes Association and the World Health Organization.1 The classification of type I and type II diabetes mellitus was retained, although the recommended criterion for the diagnosis of diabetes has become a fasting plasma glucose of 7 mmol/L or greater, or a random plasma glucose of over 11 mmol/L associated with polyuria, polydipsia and weight loss. The oral glucose tolerance test is no longer routinely recommended.
Emergency presentations of a high blood sugar
Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic non-ketotic state (HHNS) are both life-threatening acute complications of diabetes mellitus. Although important differences do exist, the pathophysiology and treatment are similar. DKA is usually seen in type I diabetes and HHNS in patients with type II, but both complications can occur in type I and type II diabetes. See Chapter 11.2 for the diagnosis and management of DKA and HHNS.
General management of diabetes mellitus
Aims of long-term blood sugar control
The aim of excellent long-term blood sugar control is an HbA1c (glycated haemoglobin) level of less than 7.5% without frequent disabling hypoglycaemia for the prevention of microvascular disease, and 6.5% in those at increased risk of arterial disease.2 This should be represented by a pre-prandial blood glucose level of 4.0–7.0 mmol/L, and a post-prandial blood glucose level of less than 9.0 mmol/L.
Antidiabetic drugs
Two newer types of oral agents are available for the treatment of diabetes. The alpha-glucosidase inhibitor acarbose acts on the gastrointestinal tract to interfere with carbohydrate digestion. The other group is the thiazolidinediones, such as pioglitazone and rosiglitazone. The thiazolidinediones act primarily by reducing insulin resistance, thereby enhancing the effect of circulating insulin. However, roziglitazone increases the risk of myocardial infarction and cardiovascular deaths, and thus should be avoided in ischaemic heart disease.3 In addition, all thiazolidinediones must be avoided in people with moderate or severe heart failure.
DIABETIC HYPOGLYCAEMIA
Hypoglycaemia most commonly occurs in type I diabetes. The critical plasma level at which hypoglycaemia manifests varies between different individuals, but symptoms are likely below a plasma glucose of 3.5 mmol/L. Common precipitants include exercise, a late meal, inadequate carbohydrate intake, ethanol ingestion and errors of insulin dosage. Hypoglycaemia may also occur in the non-diabetic patient, precipitated by a variety of conditions (see Table 11.1.2).4
Diabetic patients |
Management of hypoglycaemic coma
1 Alberti KGMM, DeFronzo RA, Keen H, et al. International textbook of diabetes mellitus. Chichester: John Wiley & Sons Ltd, 1992;31-98.
2 NICE Clinical Guideline 15. Type 1 diabetes: diagnosis and management of type 1 diabetes in children, young people and adults, July 2004. Available http://www.nice.org.uk/nicemedia/pdf/CG015NICEguideline.pdf (accessed Dec 2007)
3 Nissen SE, Wolski K. Effect of rosiglitazone on the risk of myocardial infarction and death from cardiovascular causes. New England Journal of Medicine. 2007;356:2457-2471.
4 eMedicine. Hypoglycaemia, Dec 2007. Available http://www.emedicine.com/emerg/topic272.htm (accessed)
11.2 Diabetic ketoacidosis and hyperosmolar, hyperglycaemic non-ketotic state
Introduction
Diabetic ketoacidosis (DKA) is potentially fatal and overall is a common presentation to the emergency department (ED) for insulin-dependent diabetics. Shortfalls in the quality of care for patients with DKA have been highlighted. Hyperglycaemic, hyperosmolar non-ketotic state (HHNS) is less common than DKA, but has a worse prognosis, with an increased mortality and greater morbidity, often related to underlying chronic medical disorders.
Epidemiology
An annual incidence of DKA of approximately 1:170 patients with type I diabetes has been reported.1
Clinical investigations in DKA
Urinalysis
This diagnosis is highly likely in an unwell patient in the presence of glycosuria and ketonuria.
Criteria for diagnosis
Treatment of DKA
The treatment of DKA is not complicated, but requires careful monitoring of the patient both clinically and biochemically. Ideally all observations and results should be recorded on a purpose-designed record sheet, such as an integrated care pathway that includes guidance and data recording.2
Fluids
Give patients who are not shocked 0.9% normal saline at a rate of 500 mL/h for 4 h, then 250 mL/h for the next 4 h.3 A suggested fluid regime is shown in Table 11.2.1.
Litre | Timing (hours from starting treatment) |
---|---|
First at 500 mL/h | 0–2 |
Second at 500 mL/h | 2–4 |
Third at 250 mL/h | 4–8 |
Fourth at 100 mL/h | 8–18 |
Fifth at 100 mL/h | 18–28 |
Sixth at 100 mL/h | 28–38 |
Seventh at 100 mL/h | 38–48 |