For those with Type 2 diabetes, the balancing act is somewhat easier. Many can control their blood glucose concentration reasonably well either by strict adherence to a diet, or by use of drugs. However, people with Type 2 diabetes may also need treatment with insulin to achieve satisfactory control of blood glucose concentrations, especially when they have the condition for some years.
Dietary measures are largely based on what we know about the processes of digestion, absorption and postprandial metabolism (Chapters 3 and 6). The content of simple sugars (mono- and disaccharides) in the food should be low since these lead to a rapid rise in the concentration of glucose in the blood; a high content of fibre in the diet helps to slow down the rate of absorption of carbohydrate and thus minimise the postprandial excursions in blood glucose concentration. In addition, of course, energy intake must be controlled in order to maintain as low a body weight as possible, since excess weight is associated with insulin resistance.
Several classes of drug are available for treatment of Type 2 diabetes. Acar-bose is an inhibitor of a-amylase, the pancreatic enzyme that digests starch (Section 220.127.116.11). It is given with meals and slows carbohydrate digestion, and therefore reduces postprandial excursions in blood glucose concentration. The sulphonylureas act directly upon the pancreatic P-cells to promote insulin release by closing the ATP-sensitive K+ channels in the cell membrane (see Fig. 5.4). In the longer term, the sulphonylureas also lead also to improved sensitivity to insulin. The biguanide drug, metformin, acts in a way which is not entirely clear, mainly to improve the sensitivity of the tissues to insulin, i.e. to reduce insulin resistance. In the last decade a new class of drugs has become available, the thiazolidinediones or glitazones. These drugs are activators of the transcription factor PPARy in adipose tissue. Their action was described in Section 18.104.22.168. Their overall effect is to improve sensitivity to insulin in all tissues, including skeletal muscle and the liver.
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