Insulin resistance develops gradually and often remains undetected for many years. Conventional screening frequently relies on fasting glucose or HbA1c alone, which may remain within laboratory reference ranges despite chronically elevated insulin levels.

 

For this reason, metabolic health is best assessed by recognising patterns across multiple laboratory markers rather than interpreting individual results in isolation.

 

Important

 

Laboratory reference ranges are designed primarily to identify disease, not necessarily optimal metabolic health. A result reported as "normal" may still indicate reduced metabolic efficiency when considered alongside other biomarkers, symptoms, and lifestyle factors.

​

Fasting Glucose

 

What it reflects

 

The concentration of glucose circulating in the blood after an overnight fast.

 

Why it matters

 

Fasting glucose provides a snapshot of blood sugar regulation at the time of testing. It is often the first laboratory marker assessed when evaluating metabolic health.

 

Reference values

 

Typical laboratory reference range
3.9–5.5 mmol/L (70–99 mg/dL)

 

Generally favourable for metabolic health
Often toward the lower half of the reference range while maintaining stable energy levels and without symptoms of hypoglycaemia.

 

Integra perspective

 

Normal fasting glucose does not exclude insulin resistance. Many individuals maintain apparently normal glucose levels by producing progressively larger amounts of insulin.

 

Interpret together with

​

• Fasting insulin
• HbA1c
• HOMA-IR

 

HbA1c (Glycated Haemoglobin)

 

What it reflects

 

Average blood glucose exposure over approximately the previous 2–3 months.

 

Why it matters

 

HbA1c provides a longer-term assessment of glucose regulation than a single fasting glucose measurement.

 

Reference values

 

Typical laboratory reference range
Below 5.7% (below 39 mmol/mol)

 

Generally favourable for metabolic health
Approximately 4.8–5.3% (29–34 mmol/mol), interpreted alongside other metabolic markers.

 

Integra perspective

 

HbA1c reflects glucose exposure, not insulin production. It may remain within laboratory reference ranges despite chronic hyperinsulinaemia and developing insulin resistance.

 

Interpret together with

• Fasting glucose
• Fasting insulin
• HOMA-IR

 

Fasting Insulin

 

What it reflects

 

The amount of insulin the pancreas produces to maintain fasting blood glucose.

 

Why it matters

 

Fasting insulin is one of the earliest laboratory indicators of developing insulin resistance and often becomes abnormal years before glucose levels rise.

 

Reference values

 

Typical laboratory reference range
Approximately 2–25 µIU/mL (laboratory dependent)

 

Generally favourable for metabolic health
Often 2–6 µIU/mL, with values below 8 µIU/mL commonly associated with good insulin sensitivity.

​

Integra perspective

 

A fasting insulin result near the upper end of the laboratory reference range may still indicate early metabolic dysfunction, even when glucose and HbA1c appear normal.

 

Interpret together with

​

• Fasting glucose
• HbA1c
• HOMA-IR
• Triglycerides
• HDL cholesterol

 

HOMA-IR (Homeostatic Model Assessment of Insulin Resistance)

 

What it reflects

 

An estimate of insulin resistance calculated using fasting glucose and fasting insulin.

 

Why it matters

 

HOMA-IR provides a more meaningful assessment of insulin sensitivity than fasting glucose alone.

 

Reference values

 

Typical interpretation

Lower values generally indicate better insulin sensitivity.

 

Generally favourable for metabolic health

Often below 1.0, with values above 1.5–2.0 warranting closer evaluation depending on the individual and laboratory methodology.

 

Integra perspective

​

HOMA-IR should always be interpreted within the wider clinical picture rather than as a stand-alone diagnostic tool.

​

Interpret together with

​

• Fasting glucose
• Fasting insulin
• HbA1c

 

Triglycerides (TG)

 

What they reflect

 

The principal form of circulating stored fat in the bloodstream.

 

Why they matter

 

Elevated triglycerides frequently accompany insulin resistance, excessive carbohydrate intake, and impaired metabolic flexibility.

 

Reference values

 

Typical laboratory reference range

Below 1.7 mmol/L (below 150 mg/dL)

 

Generally favourable for metabolic health

Often below 1.0 mmol/L (below 90 mg/dL)

 

Integra perspective

​

Triglycerides become considerably more informative when interpreted alongside HDL cholesterol rather than in isolation.

​

Interpret together with

​

• HDL cholesterol
• TG/HDL ratio
• Fasting insulin

 

HDL Cholesterol

 

What it reflects

 

High-density lipoprotein (HDL) participates in reverse cholesterol transport and is commonly associated with metabolic health.

 

Why it matters

 

Higher HDL levels are generally associated with better insulin sensitivity and metabolic function.

 

Reference values

 

Typical laboratory reference range

Men: above 1.0 mmol/L (40 mg/dL)

Women: above 1.3 mmol/L (50 mg/dL)

 

Generally favourable for metabolic health

Higher HDL values are generally considered favourable when interpreted alongside triglycerides and the overall lipid profile.

​

Integra perspective

​

HDL should never be interpreted independently. The relationship between triglycerides and HDL often provides more useful metabolic information than either marker alone.

​

Interpret together with

​

• Triglycerides
• TG/HDL ratio

 

Triglyceride-to-HDL Ratio (TG/HDL)

 

What it reflects

 

The relationship between circulating triglycerides and HDL cholesterol.

 

Why it matters

 

This ratio is one of the simplest practical indicators of insulin resistance and metabolic health.

 

Reference values

 

Generally favourable

Below approximately 0.9 (using mmol/L values)

(Approximately below 2.0 when using mg/dL values.)

 

Integra perspective

​

A low TG/HDL ratio is commonly associated with good insulin sensitivity and metabolic flexibility, whereas progressively higher ratios may indicate worsening metabolic health.

 

Interpret together with

​

• Fasting insulin
• HOMA-IR
• HbA1c

 

C-Peptide

 

What it reflects

 

C-peptide is released in equal amounts whenever the pancreas produces insulin and provides an estimate of the body's own insulin production.

​

Why it matters

​

It can help distinguish between reduced insulin production and excessive insulin secretion, providing additional insight into pancreatic function.

​

Reference values

​

Laboratory reference ranges vary considerably and should always be interpreted using the reporting laboratory's reference interval.

​

Integra perspective

​

C-peptide is generally not required for routine metabolic assessment but may provide valuable additional information in selected clinical situations.

​

Looking at the Whole Picture

 

No single laboratory marker can accurately define metabolic health.

​

For example:

​

• Normal fasting glucose does not exclude insulin resistance.

• Normal HbA1c does not exclude chronic hyperinsulinaemia.

• Elevated fasting insulin often precedes abnormal glucose by many years.

• Elevated triglycerides together with low HDL commonly indicate impaired metabolic health.

• HOMA-IR becomes considerably more informative when fasting glucose and fasting insulin are both available.

 

Recognising these patterns allows earlier identification of metabolic dysfunction, often well before conventional diagnostic thresholds are reached.

​

Core Principle

 

Metabolic dysfunction frequently begins with chronically elevated insulin rather than elevated blood glucose.

​

Interpreting laboratory markers as an integrated pattern—rather than as isolated values—provides a more meaningful assessment of metabolic health and supports earlier, more effective lifestyle intervention.