Clinical Use of SPISE Index for Insulin Sensitivity Assessment
The Single Point Insulin Sensitivity Estimator (SPISE) is a valuable clinical tool for assessing insulin sensitivity that performs comparably to other established fasting insulin resistance indices while offering the advantage of not requiring insulin measurement, making it more accessible and cost-effective for routine clinical use. 1
What is the SPISE Index?
SPISE is a mathematical formula calculated as:
- SPISE = 600 × HDL-C^0.185/(TG^0.2 × BMI^1.338)
- Where HDL-C is in mg/dL, TG (triglycerides) in mg/dL, and BMI in kg/m²
- Lower SPISE values indicate greater insulin resistance
- A cutoff value of 6.61 corresponds to insulin resistance 1
Clinical Applications of SPISE
1. Screening for Insulin Resistance
- Useful for identifying insulin resistance in patients with risk factors for type 2 diabetes
- Particularly valuable in settings where measuring insulin levels is costly or unavailable
- Can be used to screen patients with obesity, family history of diabetes, or other metabolic risk factors 2
2. Metabolic Syndrome Assessment
- SPISE has demonstrated high sensitivity and specificity for predicting insulin resistance in metabolic syndrome patients
- Shows better predictive ability than HOMA-IR, TG/HDL-C ratio, and other markers in some populations 3
3. Cardiovascular Risk Stratification
- SPISE-IR (calculated as 10/SPISE) has shown significant association with long-term risk of coronary heart disease
- Adjusted hazard ratio per 1 SD increase for CHD risk is approximately 1.20-1.24 4
- Comparing highest quartile with lower quartiles, SPISE-IR showed stronger association with CHD risk (HR 1.53) than other insulin resistance indices 4
4. Diabetes Risk Assessment
- SPISE performs well as a predictor for future type 2 diabetes
- Adjusted odds ratios per 1 SD increase for long-term risk of type 2 diabetes is approximately 1.62 4
Advantages of SPISE Over Other Methods
Cost-effectiveness:
- Does not require insulin measurement, unlike HOMA-IR or QUICKI
- Uses routine lipid parameters (HDL-C, triglycerides) and BMI that are commonly available
Accuracy:
- Correlation with euglycemic clamp (gold standard) is comparable to other established indices
- ROC analysis shows area under curve of 0.80 for SPISE-IR, similar to other indices (0.84) 4
Accessibility:
- Can be calculated from a single fasting blood sample plus BMI
- Suitable for large-scale clinical studies and routine practice
Clinical Implementation
When to use SPISE:
- In routine metabolic assessments when insulin measurement is unavailable
- For population screening programs
- In settings with limited resources
- For monitoring insulin sensitivity changes over time
Interpretation:
- SPISE < 6.61 suggests insulin resistance
- Can be used as a continuous variable where lower values indicate greater insulin resistance
- Consider in context with other clinical parameters
Limitations and Caveats
- SPISE was primarily validated in white adolescents and adults 1
- May need different cutoff values for different ethnic populations
- Should be interpreted in context with clinical presentation and other risk factors
- Not a replacement for glucose tolerance testing when diagnosing diabetes
Comparison with Other Insulin Sensitivity Indices
| Index | Components | Advantages | Disadvantages |
|---|---|---|---|
| SPISE | HDL-C, TG, BMI | No insulin measurement needed; Cost-effective | Newer index with less extensive validation |
| HOMA-IR | Glucose, Insulin | Well-established; Extensively validated | Requires insulin measurement; Less accurate in some populations |
| QUICKI | Glucose, Insulin | Good correlation with clamp | Requires insulin measurement |
| TG/HDL-C | TG, HDL-C | Simple calculation | Less accurate than more complex indices |
In conclusion, SPISE represents a practical and accessible tool for assessing insulin sensitivity in clinical practice, particularly valuable in settings where insulin measurement is not readily available or cost-effective.