Lipitor is a medication that is used to lower cholesterol levels in the body. It is a type of statin drug that works by inhibiting an enzyme that is involved in the production of cholesterol in the liver. While Lipitor is generally considered safe and effective, there have been concerns about its potential impact on insulin resistance.
Insulin resistance is a condition in which the body's cells become less responsive to insulin, a hormone that regulates blood sugar levels. This can lead to high blood sugar levels and, over time, an increased risk of developing type 2 diabetes. There is some evidence to suggest that statin drugs like Lipitor may worsen existing insulin resistance, although the research is not conclusive.
One study published in the journal Arteriosclerosis, Thrombosis, and Vascular Biology  found that treatment with atorvastatin (the active ingredient in Lipitor) was associated with a small but significant increase in insulin resistance in patients with high cholesterol levels. However, the study also found that the benefits of statin therapy in reducing the risk of heart disease outweighed the potential risks of worsening insulin resistance.
Another study published in the journal Diabetes Care  found that treatment with atorvastatin did not have a significant impact on insulin resistance in patients with type 2 diabetes. However, the study did note that some patients experienced an increase in blood sugar levels while taking the medication.
Overall, the evidence suggests that Lipitor may have a small impact on insulin resistance in some patients, particularly those with high cholesterol levels. However, the benefits of statin therapy in reducing the risk of heart disease generally outweigh the potential risks of worsening insulin resistance. Patients who are concerned about the potential impact of Lipitor on their insulin resistance should talk to their doctor about their individual risk factors and treatment options.