Endocrine Abstracts

A decrease in insulin sensitivity (IS) is associated with increasing visceral adiposity. An inverse correlation has been demonstrated between Intramyo-(IMTG) and intrahepatocellular triglyceride (HCTG) concentrations and IS. Patients with AA have reduced IS but IMTG and HCTG content has not been studied.

Eight patients with AA (IGF-I >ULN, median 1.83×ULN (range1.16–4.38) ((6 M), median age 39.5 (range 23–66) years, median BMI 30.6(23.5–38.6)kg/m²) and 5 healthy volunteers (HV) ((4M) median age 32(29–39) years, median BMI 27.4(24.9–29) kg/m²) were recruited.

On a Philips 3 Tesla Achieva MR scanner, full-body T1-weighted multi-slice imaging was performed and MRIcro was used to calculate fat mass (FM) in body compartments. The 1H MRS spectra obtained from liver, anterior tibialis (AT) and gastrocnemius (Gc) muscles (R leg) were analysed using jMRUI to de-convolute peaks and provide a ratio of triglyceride content/water (as % water content).

AA (fasting glucose median 5.3 mmol/l, range 4.7–6.2) patients had significantly less HCTG content c.f. HV (median 0.1%, range 0–5.5 vs 12%, 2.1–22, P=0.01) despite no overall differences in weight or FM distribution.

There was no difference in IMTG content in either muscle (CH2 moiety) as % water; (Gc), AA median 0.81(0.61–4.9)% vs HV 2.73(0.31–9.12)%, P=1, (CH3 moiety) AA 0.32(0–0.58)% vs HV 0.33(0–0.45)%, P=1, (TA) (CH2 moiety) AA 0.16(0–2.07)% vs HV 0.73(0.33–9.12)%, P=0.21, (CH3 moiety) AA 0(0–0.29)% vs HV 0.12(0–9.12)%, P=0.33).

HCTG content is significantly reduced in AA compared to healthy volunteers. Patients with known AA have reduced IS and acromegaly appears to be unique in having impaired IS associated with low hepatic triglyceride. The mechanisms involved require further exploration, but may relate to the lipolytic actions of GH.