Diabetes occurs when insulin is not adequately released from the pancreas when required or when inactivity and fat deposition or weight gain prevent the action of insulin on the body’s cells. In the latter situation, when insulin is present in abundance but cannot execute the desired actions, insulin resistance is said to have developed. Other factors contributing to a high blood glucose level may be overeating or excessive production of glucose by the liver which is actually a storehouse of glucose.
The management of diabetes begins with diet, exercise and lifestyle changes. When not controlled by these measures, blood glucose can be controlled by oral medications and insulin injections. Used singly or in combination, the medications need frequent adjustments and blood glucose needs regular monitoring.
Medications for diabetes
Oral drugs act by various mechanisms of action, have unique pharmacologic properties like potencies and duration of action and varying safety profiles. These may be chosen from one of the five distinct classes of medications, which are:
- Sulphonylureas: These stimulate pancreas to release more insulin.
- Meglitinides: These also cause pancreas to release more insulin.
- Biguanides: These medications reduce glucose levels by facilitating uptake of blood sugar by the body’s cells
- Thiazolidinediones: These make muscle and fat more sensitive to the action of insulin
- Alpha-glucosidase inhibitors: These prevent absorption of glucose from food in intestine
Since most of these agents undergo chemical changes and are assimilated in the liver and then excreted by the kidney, disease adjustments may be required in disease conditions.
Medications that increase insulin release in pancreas
Sulphonylureas stimulate the release of insulin from the pancreas. These may slightly improve insulin resistance. This class of medication includes agents like acetohexamide, chlorpropamide, tolazamide, glyburide, glipizide and glimeperide. Sulphonylureas are started at low doses, and then increased gradually over 1-2 weeks and the recommended maximum doses vary considerably. Depending upon the blood glucose levels and duration of action of the various agents, the long or short acting agents can be chosen for once, twice, or more frequent dosing. These are taken before meals.
Sulphonylureas are most likely to cause hypoglycemia, a precipitous fall in blood glucose. Weight gain is another side effect seen with sulphonylureas and makes these agents unfit for the obese diabetics. Some of these agents may need to be administered with caution in elderly and in those with compromised kidney function.
Like sulphonylureas, metiglinides cause release of insulin from pancreas. This class includes the drugs like repaglinide and retiglinide. The action of these agents does not last long and these have lesser risk of hypoglycemia; these are taken immediately before a meal as these have a quick onset of action and allow flexibility of dosing in patients with an irregular meal intake.
Medications that decrease glucose production
Metformin is a drug that belongs to the class of medications called biguanides and acts by reducing the production of glucose from the liver. Additionally, it sensitizes the liver and other tissues to action of insulin. It has a favorable effect on body weight, and hence forms a choice of therapy for the overweight diabetics but should be used with caution in kidney failure. Extended release preparations allow a convenient once daily dosing. Metformin also improves the lipids and fats in blood. Metformin makes a preferred choice in fat diabetics as it only improves the blood glucose control but also contributes to maintaining better fat levels in blood. Metformin may cause an altered taste in mouth, stomach discomfort or a sensation of vomiting that can be offset by gradually increasing the dosing and taking the drug with meals. It is unlikely to cause hypoglycemia and very rarely makes the blood more acidic.
Medications that make tissues more sensitive to action of insulin
Troglitazone, rosiglitazone and pioglitazone belong to the class of medications called thiazolidinediones. These agents have become a preferred choice for diabetics with or at risk of heart disease as they favorably affect the fats in blood and also the blood pressure, both of which are risk factors for heart disease. These agents predominantly improve sensitization of muscle and fat cells to insulin and also reduce glucose production in the liver. Like most other drugs, these are assimilated in the liver and are excreted by the kidney. These agents do not cause hypoglycemia. Periodic monitoring of liver function is required with this class of drugs. These can be safely combined with other drugs and have found usefulness in reducing the requirements of insulin though the effects of these agents may not be seen immediately. These agents can be conveniently taken once or twice a day without relation to meals.
Medications that reduce glucose absorption
The alpha-glucosidase inhibitors acarbose and miglitol reduce the absorption of glucose from the intestine. These are best taken three times a day with the first bite of every major meal. These are particularly useful when the fasting blood glucose levels are not very high but levels after meals shoot up. Abdominal discomfort, bloating, flatulence and diarrhea are the common adverse effects though these can be reversed by stopping the drug. These drugs warrant caution in liver and kidney dysfunction. When used alone, these do not cause hypoglycemia.
Insulin
As a last resort, when oral medications fail or are not enough to control the blood sugar levels, insulin is initiated. Insulin can be combined with oral therapy or used alone and is injected using special syringes. Hypoglycemia is the major risk with the use of insulin. Insulin is available as short, rapid, intermediate and long acting preparations. Depending upon the patterns of rise of blood glucose, the rapid action insulin may be taken 15 to 30 minutes before meals or a mixture of the short and long acting preparations may be used to meet the requirements of mainlining glucose levels after meals and then throughout the day.
Prevent, monitor and treat diabetes
If you are more than 45 years old and overweight or have diabetes running in your family, you may be at risk for diabetes. You should undergo screening for high blood glucose periodically. Management of diabetes needs a multipronged approach with diet, exercise, oral drugs and insulin. Regular monitoring of blood glucose is important. Effective management can help to prevent the complications of the chronic disease which is a silent killer, if left untreated.
