What is the relationship between Duloxetine (Cymbalta) and diabetes?

From the Guidelines

Cymbalta (duloxetine) is a recommended initial pharmacologic treatment for neuropathic pain in diabetes, with a typical dose of 60mg once daily, and can be safely used by most people with diabetes, but requires monitoring as it may affect blood sugar levels in some patients. According to the most recent and highest quality study, 1, duloxetine is one of the recommended initial pharmacologic treatments for neuropathic pain in diabetes, along with pregabalin and gabapentin. The medication works by increasing serotonin and norepinephrine levels in the brain, which helps manage pain signals and mood disorders. When used for diabetic neuropathy, Cymbalta helps reduce the burning, tingling, and pain sensations by modifying how the brain perceives these pain signals.

Some key points to consider when using Cymbalta for diabetic neuropathy include:

• Monitoring blood glucose levels more frequently when starting or changing doses, as some individuals may experience changes in blood sugar control 1
• Starting with a dose of 30mg daily and increasing to 60mg daily after one week, if necessary
• Taking Cymbalta at the same time each day and swallowing capsules whole
• Not stopping the medication abruptly, as this can cause withdrawal symptoms
• Being aware of potential side effects, such as nausea, dry mouth, constipation, decreased appetite, and fatigue

It's also important to note that optimizing glucose control is crucial in preventing or delaying the development of neuropathy in patients with type 1 diabetes and slowing the progression of neuropathy in patients with type 2 diabetes 1. Additionally, assessing and treating patients to reduce pain related to diabetic peripheral neuropathy and symptoms of autonomic neuropathy can improve quality of life 1.

From the FDA Drug Label

Glycemic Control in Patients with Diabetes As observed in DPNP trials, duloxetine delayed-release capsules treatment worsened glycemic control in some patients with diabetes. In three clinical trials of duloxetine delayed-release capsules for the management of neuropathic pain associated with diabetic peripheral neuropathy [see Clinical Studies (14. 4)], the mean duration of diabetes was approximately 12 years, the mean baseline fasting blood glucose was 176 mg/dL, and the mean baseline hemoglobin A 1c (HbA 1c) was 7. 8%. In the 12-week acute treatment phase of these studies, duloxetine delayed-release capsules were associated with a small increase in mean fasting blood glucose as compared to placebo. In the extension phase of these studies, which lasted up to 52 weeks, mean fasting blood glucose increased by 12 mg/dL in the duloxetine delayed-release capsules group and decreased by 11. 5 mg/dL in the routine care group. HbA 1c increased by 0.5% in the duloxetine delayed-release capsules group and by 0.2% in the routine care group.

• Cymbalta (duloxetine) and diabetes: The use of duloxetine delayed-release capsules may worsen glycemic control in some patients with diabetes.
• Key findings:
  • Small increase in mean fasting blood glucose compared to placebo in the 12-week acute treatment phase.
  • Increase in mean fasting blood glucose by 12 mg/dL in the duloxetine delayed-release capsules group and decrease by 11.5 mg/dL in the routine care group in the extension phase.
  • Increase in HbA1c by 0.5% in the duloxetine delayed-release capsules group and by 0.2% in the routine care group.
• Clinical decision: Caution is advised when using duloxetine delayed-release capsules in patients with diabetes, as it may worsen glycemic control 2.

From the Research

Cymbalta and Diabetes

• Cymbalta, also known as duloxetine, is an antidepressant that has been studied in the context of diabetes and diabetic neuropathy 3, 4, 5.
• The efficacy of duloxetine in treating depression and neuropathic pain in diabetic patients has been demonstrated in some studies, but its effectiveness compared to other antidepressants is still uncertain 3.
• Duloxetine has been shown to increase blood pressure in a dose-dependent manner and has a risk of interactions with other drugs due to its metabolism by cytochrome P450 isoenzymes 3.

Effects on Glycemic Control

• Some studies suggest that duloxetine may have a modest effect on glycemic control, with a small increase in fasting plasma glucose (FPG) and HbA(1c) levels in patients with diabetic peripheral neuropathic pain (DPNP) 5.
• However, other studies have found that duloxetine does not significantly alter FPG and HbA(1c) levels compared to placebo treatment in patients with diagnoses other than DPNP 5.
• The use of selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, has been associated with improvements in glycemic control in depressed patients with diabetes 6, 7.

Comparison with Other Antidepressants

• SSRIs are generally considered to be a preferable choice for treating depression in patients with diabetes due to their favorable effects on glycemic control 4, 6, 7.
• Tricyclic antidepressants (TCAs) and noradrenergic antidepressants may worsen glycemic control and are not recommended as a first-line treatment for depression in patients with diabetes 6, 7.
• The choice of antidepressant should be individualized based on the patient's specific needs and medical history, taking into account the potential effects on glycemic control and other metabolic parameters 4, 7.