How Tesamorelin Affects HOMA-IR and Insulin Sensitivity

Tesamorelin preserves HOMA-IR and insulin sensitivity through pulsatile, not continuous, GH release:

1. Inter-pulse insulin sensitivity recovery: Between GH pulses, insulin sensitivity returns to baseline. The negative feedback loop (IGF-1 stimulates somatostatin, somatostatin suppresses GH) ensures that GH exposure remains pulsatile rather than continuous.
2. Visceral fat reduction improves hepatic insulin sensitivity: As VAT decreases, portal free fatty acid flux to the liver drops, hepatic insulin clearance improves, and HOMA-IR moves favourably over time.
3. Direct clamp evidence: Stanley et al. (2011, PMID 20943777) used a hyperinsulinaemic-euglycaemic clamp in healthy men on 2 mg/day for 2 weeks. Glucose disposal rate was unchanged (p=0.61) and fasting glucose was unchanged (p=0.93). This is the most direct human evidence that tesamorelin does not impair peripheral insulin sensitivity.
4. Fasting insulin trends in responders: In the Falutz responder cohort, fasting insulin dropped 1.1 µIU/mL at week 26 (vs +5.7 in non-responders, p=0.011), suggesting that VAT reduction translates into improved hepatic insulin sensitivity downstream.

Standard dose (1.4-2 mg/day, subcutaneous):

• Insulin-stimulated glucose uptake (clamp): unchanged at 2 weeks (Stanley 2011, p=0.61)
• Fasting insulin (responders): -1.1 µIU/mL at week 26 (Stanley CID 2012)
• Fasting insulin (non-responders): +5.7 µIU/mL at week 26 (p=0.011 vs responders)
• HOMA-IR: trends favourable in responders, flat or slightly worse in non-responders

Calculation: HOMA-IR = (fasting glucose mg/dL × fasting insulin µIU/mL) / 405. Example: glucose 90, insulin 8 = (90 × 8) / 405 = 1.78 (low normal). Insulin 12 = 2.67 (mid range). Insulin 18 = 4.00 (insulin resistant).

Timeline: HOMA-IR improvements track VAT reduction. Detectable changes by week 12-26 in responders.

Baseline: Fasting glucose, fasting insulin, calculate HOMA-IR before starting. This is the most important baseline number for metabolic monitoring on any GH-axis compound.

During use:

• Fasting insulin and HOMA-IR at week 12
• Repeat at week 26
• Every 12 weeks thereafter if continuing

Interpretation:

• HOMA-IR <1.5: insulin sensitive
• HOMA-IR 1.5-2.5: borderline
• HOMA-IR 2.5-5.0: insulin resistant
• HOMA-IR >5.0: significant insulin resistance

On tesamorelin:

• HOMA-IR drop or flat in responders: expected, continue
• HOMA-IR rise in non-responders: discontinue (no body composition return for metabolic cost)
• Baseline HOMA-IR >5.0: address underlying metabolic disease first; consider metformin or GLP-1 before tesamorelin

Optimising insulin sensitivity on tesamorelin:

• Inject at bedtime on an empty stomach. Elevated insulin at injection time blunts both GH release and tesamorelin's metabolic benefit.
• Add a low-dose GLP-1 (semaglutide, tirzepatide) if baseline HOMA-IR is above 3.0. The combination targets metabolic syndrome from two angles.
• Maintain ≥150 minutes/week of moderate aerobic exercise. Aerobic conditioning independently improves HOMA-IR and amplifies tesamorelin's benefit.

If HOMA-IR rises:

• Verify with two readings 4-8 weeks apart (insulin assay variability is high)
• Check VAT response. If VAT is responding, the HOMA-IR drift is unusual and suggests a confounding factor (other compound, lifestyle change, illness)
• If VAT is not responding, discontinue. Non-responders worsen on HOMA-IR with no compositional return.

Avoid stacking with insulin-resistance compounds:

• Do not run tesamorelin with MK-677 (Chapman 1996: fasting glucose +26% at 4 weeks, HOMA-IR rises)
• Do not run with exogenous HGH at bodybuilding doses (continuous GH exposure impairs insulin sensitivity, defeats tesamorelin's pulsatile advantage)