A recent study assesses associations between the risks of cardiovascular disease, heart failure and mortality with different diabetes drugs in people with type 2 diabetes.
Type 2 diabetes is a metabolic disorder characterized by high blood sugar, insulin resistance and the relative lack of insulin. The disease affects almost 10% of the general population, including over 25% of the population over the age of 65. The proportion of the population with type 2 diabetes has increased over the past decades and is expected to continue to rise.
The disease puts patients at greater risk of cardiovascular disease, heart failure, amputation, kidney disease, blindness and mortality. Treatment for diabetes involves lifestyle changes such as weight management, diet, exercise and prescription medications. The drug categories prescribed to treat type 2 diabetes include glitazones, gliptins, sulphonylureas, metformin and insulin. Drug treatment involves single- or multi-drug. Past clinical studies demonstrated that several drugs have been associated with increased risk of heart failure, raising questions about the risks and benefits of taking a particular drug. Little is known about the long-term effects of taking a single or a combination of drugs to treat type 2 diabetes.
A study recently published in the British Medical Journal examined the association between commonly prescribed medications for type 2 diabetes and the risk of mortality, heart failure and cardiovascular disease. The study evaluated the risks with single-drug therapy as well as with treatment involving two or more drugs.
The large cohort study spanned a period of 8 years and examined the primary care, hospital and mortality records of 469,688 British patients with type 2 diabetes between the ages of 25 and 84. The authors used Cox proportional hazard models to assess the associations between the different classes of diabetes drugs and the risk of mortality, heart failure and cardiovascular disease. The authors adjusted for potential confounders including age, sex, numbers of years since the diabetes diagnosis, smoking status and ethnicity.
In total, 58.4% of the patients in the study received prescriptions for one or more diabetes drugs. The authors found relevant differences between different diabetes drugs and the risk the three key outcomes. The results are recorded below, by medication or medication combination, and the outcomes are listed in the order of all-cause mortality, heart failure, and cardiovascular disease unless otherwise noted:
- Glitazones were associated with decreased risk in all three outcomes (23%, 26%, 25%) as compared to non-use;
- Gliptins were associated with decreased risk in two of the three outcomes (18% risk of all cause mortality and a 14% decreased risk of heart failure) as compared to non-use;
- Metformin was associated with a significantly decreased risk of all three outcomes (41%, 30%, 24%) as compared to non-use;
- Compared with non-use, sulphonylureas were associated with a 10% risk of all cause mortality;
- Insulin as mono-therapy was associated with an increased risk in all three outcomes (47%, 32%, 23%);
- Dual treatment of metformin and gliptins as well as metformin, gliptins and sulphonylureas decreased the risk of all three outcomes (47%, 38%, 33%; 51%, 40%, 30%);
- Dual treatment with metformin and glitazones was associated with a decreased risk of all three outcomes (45%, 50%, 54%);
- Dual treatment with sulphonylureas and glitazones was associated with a decreased risk of two outcomes (35% for heart failure and 25% for cardiovascular disease);
- Triple treatment with metformin, glitazones and sulphonylureas was associated with a decreased risk of all three outcomes (45%, 50%, 54%).
The study highlighted important differences in the level of risk from cardiovascular disease, heart failure, and all-cause mortality when using diabetes drugs either separately or in combination as well as when compared with no drug treatment. These results may have implications for prescribing diabetes drugs. The authors of the study did not account for levels of adherence or dosage information.
Written By: Lynn Kim