Background: Growth hormone (GH) excess is associated with increased insulin resistance (IR). Lanreotide autogel (Autogel) reduces GH-levels effectively in patients with active acromegaly. However, the effect of somatatostatin analogues on IR and (-cell function (HOMA %B) is complex and unpredictable. Our study prospectively monitored IR and related metabolic parameters in acromegalics treated with Autogel.
Methods: Nine patients (P) with active acromegaly, who were switched to Autogel from a different analogue after a wash-out period of four months (4 P) or who were commenced on Autogel (5 P) after failed surgery. Measurements: fasting levels of glucose (FPG), insulin, IGF-1, IGFBP-3, IGFBP-1, lipids HbA1c and GH day curve at the start of treatment (visit (V0) and six months (V6) on treatment with Autogel).
Results: Compared to V0, the following measurements were significantly reduced at V6: mean GH (5.3 mU/L vs 2.0 mU/L P=0.01); IGF-1 (38.7 nmol vs 20.1 nmol/l, P=0.008); IGFBP3 (3.27 mg/L vs. 2.62 mg/L, P=0.007); insulin (15 mU/L vs. 9.1 mU/L, P=0.04). GH <5 mU/L was achieved in 7/9 P. HOMA-IR was reduced by 39% after treatment with Autogel (P=0.047), but at the same time HOMA %B showed a reduction from a mean 95% to a mean 59% (P=0.045). FPG did not change significantly, but HbA1c deteriorated (5.8% vs 6.2%, P<0.0001,). HDL-C increased by 15% (P=0.012). HOMA-IR correlated with mean log GH (r=0.47, P=0.012), IGF-1 (r=0.68, P<0.001), IGFBP3 (r=0.69, P<0.001), negatively with log IGFBP1 (r=−0.56 P=0.002) and HDL-C, (r=−0.41, P=0.034).
Conclusion: 78% of patients achieved safe GH levels during the study. Treatment with Autogel resulted in a significant reduction of IR which was accompanied by a 15% increase in HDL. However, HOMA %B decreased also significantly with no change in FPG, but an increase in HbA1c, suggesting post-prandrial disturbances in glucose homeostasis in patients on Autogel.