From the Guidelines
Fasting insulin assessment should be conducted after an 8-12 hour overnight fast, with management of elevated levels focusing on lifestyle modifications and medication, prioritizing metformin as the first-line treatment, as per the most recent guidelines 1.
Key Considerations for Fasting Insulin Assessment
- Normal fasting insulin levels are typically below 25 μIU/mL.
- Lifestyle modifications include a low-carbohydrate diet, regular exercise (150 minutes of moderate activity weekly), and weight loss of 5-10% if overweight.
- Metformin is the first-line medication, usually starting at 500 mg daily with meals, gradually increasing to 1000-2000 mg daily in divided doses as tolerated, based on the patient's eGFR and tolerance 1.
Management of Elevated Fasting Insulin Levels
- The primary goal is to improve insulin sensitivity and reduce insulin resistance.
- Medications such as GLP-1 receptor agonists (e.g., semaglutide) and SGLT-2 inhibitors (e.g., empagliflozin) can be considered in addition to metformin.
- Regular monitoring should include fasting insulin levels every 3-6 months, along with glucose, HbA1c, and lipid profiles.
Importance of Fasting Insulin Assessment
- Hyperinsulinemia often precedes type 2 diabetes and increases cardiovascular risk by promoting inflammation, dyslipidemia, and hypertension.
- Early detection and management of elevated fasting insulin levels can prevent progression to diabetes and metabolic syndrome, ultimately reducing morbidity, mortality, and improving quality of life 1.
From the Research
Fasting Insulin Assessment Guidelines
- Fasting insulin levels can be used to identify prediabetes, with a level > 9.0 microIU/mL correctly identifying 80% of affected patients 2
- Elevated fasting insulin levels are associated with insulin resistance, which is a major pathophysiologic abnormality in type 2 diabetes 3, 4, 5
- The homeostasis model assessment of insulin resistance (HOMA-IR) index can also be used to predict prediabetes, with increased index values indicating a higher likelihood of identifying prediabetes 2
Management of Elevated Fasting Insulin Levels
- Intermittent fasting has been shown to be effective in reducing fasting insulin levels and improving insulin sensitivity in patients with type 2 diabetes 6
- Medications such as metformin and pioglitazone can also improve insulin sensitivity and reduce fasting insulin levels 3, 4, 5
- A fixed combination of metformin and pioglitazone has been shown to provide greater improvement in insulin resistance than metformin alone 4
- Sitagliptin and metformin added to pioglitazone monotherapy have been shown to improve glycemic control and insulin resistance in poorly controlled type 2 diabetes mellitus patients 5
Assessment and Monitoring
- Fasting insulin levels should be monitored regularly in patients with prediabetes or type 2 diabetes to assess insulin resistance and adjust treatment as needed 2
- The use of predictive clinical and laboratory models, such as the one developed in the study by 2, can help identify patients with prediabetes and guide treatment decisions.