Diabetes mellitus and hyperlipidaemia

16 Diabetes mellitus and hyperlipidaemia




Diabetes Mellitus


Diabetes mellitus (DM) is characterized by a failure of glucose homeostasis leading to hyperglycaemia. This may result from a lack of insulin secretion, from a failure of insulin effect, or from both. It is associated with disturbances not only in carbohydrate metabolism but also in that of fat and protein.


Insulin is an anabolic hormone that is secreted from pancreatic β-cells into the portal vein after a rise in blood glucose. Other hormones involved in glucose homeostasis include glucagon and gut peptides such as glucagon-like peptide (GLP)-1 and gastric inhibitory peptide (GIP), which are also released in response to food.






Who classification of diabetes





Type 2 diabetes mellitus


Type 2 DM (> 90% of total) results from a progressive fall in insulin secretion with, in addition, resistance to the action of insulin. It is frequently associated with obesity and the ‘metabolic syndrome’ (p. 429). Early in the disease, there may be high levels of circulating insulin, in contrast to type 1 diabetes. Hyperglycaemia results from a progressive failure of the pancreatic β-cells to maintain high levels of insulin secretion to overcome peripheral resistance. The diagnosis is therefore often delayed since endogenous insulin levels are initially sufficient to prevent ketogenesis and a catabolic state. Intercurrent illness, with increased insulin resistance secondary to release of stress response hormones, is associated with worsening glycaemic control and consequent dehydration. The presentation is often with a concurrent illness in an adult with a history of polyuria, polydipsia and malaise over some weeks.


Higher-risk population groups that may benefit from screening for type 2 diabetes include:




Although insulin therapy is sometimes required in the short term following diagnosis, the mainstay of treatment for patients with type 2 diabetes is advice on diet, exercise, weight loss and healthy lifestyle. Oral antidiabetic therapy is frequently successful, particularly for the first few years, but many patients ultimately require insulin to achieve satisfactory glycaemic control.



Other types of diabetes








Diagnosis


The diagnosis of diabetes should never be made on a single high blood sugar reading, unless the clinical history is strongly suggestive of the diagnosis. During periods of intercurrent illness (such as myocardial infarction) the stress response hormones may result in a transient rise in blood sugar; follow-up blood sugar levels will help to exclude type 2 diabetes. A glucose tolerance test is only required for borderline cases and to detect impaired glucose tolerance (IGT).




Management of diabetes


Patients must take the lead in the management of their diabetes. Their general care must be multi-disciplinary and involve all healthcare workers. Educational programmes are available and should be emphasized continuously.


The aims of management are to:





There is good evidence to suggest that good glycaemic control is associated with the lowest risk for long-term complications in type 1 as well as type 2 diabetes.



Insulin therapy


Insulin is the only therapy suitable for the treatment of type 1 diabetes and in cases where endogenous insulin production has been significantly reduced, such as haemochromatosis. Interruptions in insulin therapy render these individuals at risk of ketosis. Insulin is also used to cover periods of intercurrent illness in type 2 diabetes when insulin resistance is increased, or there are concerns that hepatic or renal clearance of an oral drug may be impaired. Progressive β-cell failure is seen in type 2 diabetes and thus oral antidiabetic agents may with time fail to control glycaemia adequately. While there is often resistance to injectable therapy, either through patient preference or a fear of weight gain, initiation of insulin in this group of patients should not be delayed.



Insulin formulations (Table 16.1)


In developed countries most patients use human insulin rather than animal-derived insulin preparations. Insulin in the UK is provided at a concentration of 100 U/mL, although some countries use 40 U/mL. Diabetics who travel should be aware of this. Very rarely, insulin five times this strength, at 500 U/mL, is used in cases of severe insulin resistance.







Principles of insulin treatment


Absorption of insulin will be influenced by the site of injection (fastest from the abdomen, then from the arm and slowest from the thigh). The speed of insulin effect will also be increased in the context of increased local blood flow, such as during exercise. Insulin regimens vary, having an emphasis on either simplicity or flexibility. The most successful regimen would mimic normal physiological release of insulin, with a low level of basal insulin present at all times and superimposed prandial peaks of insulin.










Oral antidiabetic drugs (Table 16.2)




Insulin sensitizing agents







Other therapies



Incretins








Practical management of type 1 DM



Apr 2, 2017 | Posted by in GENERAL SURGERY | Comments Off on Diabetes mellitus and hyperlipidaemia

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