From the Guidelines
Fasting insulin levels are a crucial indicator of insulin resistance and metabolic health, with high levels often signifying an increased risk of developing type 2 diabetes, metabolic syndrome, and other health issues 1. When interpreting fasting insulin levels, it's essential to consider the context of the patient's overall health and medical history.
- Fasting insulin levels can help identify insulin resistance, a precursor to type 2 diabetes and other metabolic disorders.
- Normal fasting insulin levels typically range from 2-25 μIU/mL, with optimal levels usually below 10 μIU/mL.
- High fasting insulin levels have been linked to poor outcomes in patients with certain types of cancer, such as breast and colorectal cancer 1. In clinical practice, fasting insulin levels should be used in conjunction with other diagnostic tests, such as fasting glucose tests, to provide a comprehensive assessment of a patient's metabolic health.
- Lifestyle changes, including weight loss, regular exercise, and reducing refined carbohydrates, can help improve insulin sensitivity and reduce the risk of developing metabolic disorders.
- The American Diabetes Association recommends using fasting insulin levels as a diagnostic tool for insulin resistance and type 2 diabetes, particularly in patients with a high risk of developing these conditions 1.
From the Research
Fasting Insulin Level
- Fasting insulin level is a measure of insulin resistance, which is a common finding in diabetes mellitus 2
- It can serve as a measure of efficacy of therapies for diabetes mellitus, such as exercise, exogenous insulin, sulfonylureas, and PPAR gamma agonists 2
- Elevated fasting insulin levels may be more specific for insulin resistance, while the QUICKI method may be more sensitive 2
Insulin Resistance
- Insulin resistance has a complex etiology, with multiple manifestations across the organ systems involved in glucose homeostasis 3
- Glucose-lowering drug therapies that target insulin resistance can utilize different mechanistic approaches, such as metformin and thiazolidinediones 3
- Insulin resistance can be measured using various methods, including fasting serum insulin levels, but these levels are poor measures of insulin resistance 4
Measurement of Insulin Resistance
- Measurements of fasting serum insulin levels should be reserved for large population-based epidemiological studies, where they can provide valuable data on the relationship of insulin sensitivity to risk factors for diabetes and cardiovascular disease 4
- Fasting insulin level can be used as a marker of insulin resistance, particularly in subjects with abnormal glucose tolerance 5
- However, correlations between insulin level and the degree of insulin resistance are weaker in subjects with impaired glucose tolerance and non-insulin-dependent diabetes 5
Clinical Implications
- Clinicians should shift from identifying "insulin resistance" to identifying risk factors, such as fasting glucose and lipid levels, hypertension, and central obesity 4
- Individuals "at risk" of diabetes and atherosclerotic cardiac disease can be identified simply and inexpensively, using classic clinical techniques, such as history-taking, physical examination, and very basic investigations 4