From the Guidelines
Fasting insulin levels should be interpreted in the context of overall health status and symptoms, with normal levels typically ranging from 2-25 μIU/mL (14-174 pmol/L), and optimal levels below 10 μIU/mL, as elevated levels may indicate insulin resistance and increased risk for metabolic disorders 1. To interpret fasting insulin results properly, it is essential to fast for 8-12 hours before testing and consider the result alongside other metrics like fasting glucose and HbA1c. Some key points to consider when interpreting fasting insulin levels include:
- Elevated insulin levels may indicate prediabetes, metabolic syndrome, or polycystic ovary syndrome, while very low levels could suggest pancreatic insufficiency or type 1 diabetes.
- The homeostatic model assessment of insulin resistance (HOMA-IR) calculation, which combines fasting insulin and glucose values, provides a more comprehensive assessment of insulin resistance.
- Lifestyle modifications, including weight loss, regular exercise, and reducing refined carbohydrates, can improve insulin sensitivity if levels are elevated, as supported by studies such as 1 and 1.
- It is crucial to discuss results with a healthcare provider who can interpret them in the context of overall health status and symptoms, taking into account the latest guidelines and recommendations, such as those outlined in 1 and 1.
- Recent studies, such as 1, emphasize the importance of considering individual factors, including age, weight, and overall health, when interpreting fasting insulin levels and developing treatment plans.
- Additionally, studies like 1 highlight the significance of waist circumference and visceral fat in assessing metabolic risk and insulin resistance, particularly in children and adolescents.
From the Research
Interpreting Fasting Insulin Levels
Fasting insulin levels can be used to assess insulin sensitivity and identify prediabetes. The following points summarize how to interpret fasting insulin levels:
- Fasting insulin levels can be used to calculate the Quantitative Insulin Sensitivity Check Index (QUICKI), which is a measure of insulin sensitivity 2
- A higher fasting insulin level is associated with a higher likelihood of prediabetes, with a level above 9.0 microIU/mL correctly identifying prediabetes in 80% of affected patients 3
- Fasting insulin levels can be used in combination with other clinical and laboratory attributes, such as the homeostasis model assessment of insulin resistance (HOMA-IR), to predict the presence of prediabetes 3
Factors Affecting Fasting Insulin Levels
Several factors can affect fasting insulin levels, including:
- Insulin resistance, which can be improved with medications such as metformin and pioglitazone 2, 4
- Obesity, which is a common comorbidity in patients with prediabetes and type 2 diabetes 3, 5
- Age, with older age being associated with a higher likelihood of prediabetes 3
- Diastolic blood pressure, with higher blood pressure being associated with a higher likelihood of prediabetes 3
Clinical Applications of Fasting Insulin Levels
Fasting insulin levels have several clinical applications, including:
- Identifying patients with prediabetes, who may benefit from lifestyle interventions or pharmacological therapy to prevent progression to type 2 diabetes 3
- Monitoring the effectiveness of treatments for insulin resistance, such as metformin and pioglitazone 2, 4
- Assessing the risk of cardiovascular disease, which is increased in patients with insulin resistance and type 2 diabetes 4