Growth Hormone Replacement Therapy Can Raise Incidence of Type 2 Diabetes

It is known that growth hormone deficiency (GHD) can be associated with insulin resistance and diabetes.  Therefore, a study was done (and published November 10, 2011, in Diabetes Care ahead of print) to examine the incidence of diabetes during growth hormone replacement therapy (GHRT); the study also looked at how GHRT affects fasting plasma glucose concentrations and A1c in adults with GHD.
Illustration depicting a computer screen capture with a hormone replacement therapy conceptThe study—published as “Incidence of Diabetes Mellitus and Evolution of Glucose Parameters in Growth Hormone-Deficient Subjects During Growth Hormone Replacement Therapy:  A long-term observational study”—involved 5,143 GH-deficient patients.  Of the subjects, 49.9% of them were male.  The mean age was 49±13 years old, and BMI was 29.1±5.9 kg/m2.  The mean observation was 3.9 years (range 0.01-13 years), which gave a total patient years of 20,106.

The researchers compared the observed number of cases (O) to the expected number of cases (E).  Also, they used reference rates from Sweden, 3 other regions in Europe, and 1 US region.

There were 523 patients who developed diabetes during the study.  Those who did develop diabetes shared these characteristics when compared to the people who did not develop diabetes:

  • They were older.
  • They had a high BMI.
  • They had a larger waist circumference.
  • They had higher triglyceride concentrations and blood pressure,
  • They had lower HDL cholesterol concentrations.

The incidence of diabetes was 2.6/100 patient years, and it was equal in both males and females.

Also, when compared to the Swedish reference, diabetes incidence was significantly increased (O/E=6.02, p<0.0001).  When compared with the 4 other populations, diabetes incidence also increased (O/E=2.11-5.22, p<0.0001).

It was noted that O/E increased with BMI; it decreased with duration of GHRT (p<0.0001)

For those patients who didn’t develop diabetes, fasting plasma glucose concentrations increased from 84.4±0.9 mg/dL to 89.5±0.8 mg/dL (0.70 mg/dL/year).  In those same patients, A1c increased from 4.74±0.04% to 5.09±0.13% (0.036%/year).  Both of these increases were seen over 6 years of GHRT.

In conclusion, it seems that diabetes incidence is increased in GHD patients who receive GHRT and who exhibit an adverse risk profile at baseline.  When dealing with patients who meet this description, glucose homeostasis parameters should be carefully monitored.

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