Individualized low-dose growth hormone (GH) treatment in GH-deficient adults with childhood-onset disease: metabolic effects during fasting and hypoglycemia

The effect of growth hormone (GH) replacement on blood glucose homeostasis in adult nondiabetic patients with GH deficiency: real-life data from the NordiNet® International Outcome Study

OBJECTIVE

To assess the effect of 4 years' growth hormone (GH) replacement on glucose homeostasis and evaluate factors affecting glycosylated haemoglobin (HbA_1c ) in adults with growth hormone deficiency (GHD).

DESIGN

NordiNet^® International Outcome Study, a noninterventional study, monitors long-term effectiveness and safety of GH replacement [Norditropin^® (somatropin), Novo Nordisk A/S] in real-life clinical practice.

PATIENTS

Nondiabetic patients (n = 245) with adult-onset GHD (age ≥20 years at GH start), ≥4 years' GH replacement and HbA_1c values at baseline and 4 years were included in the analysis.

MEASUREMENTS

Changes from baseline (∆) to 4 years in HbA_1c , fasting plasma glucose (FPG), IGF-I, lipids (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, total cholesterol, triglycerides), waist circumference, glycaemic (HbA_1c <5·7%; HbA_1c , 5·7-6·5%; HbA_1c , ≥6·5%) and metabolic health status were evaluated. Effects of baseline HbA_1c , gender, baseline age, average GH dose and baseline body mass index (BMI) on ΔHbA_1c were investigated. The models were adjusted for concomitant medication use.

RESULTS

Mean (standard deviation) baseline HbA_1c was 5·13 (0·65)% and remained at the same level at 4 years. Age at treatment start (P = 0·0094) and BMI (P = 0·0008) had a significant impact on ∆HbA_1c . At 4 years, 85% of patients with HbA_1c <5·7% (normal levels) at baseline and 55% of patients with HbA_1c 5·7-6·5% (impaired glucose tolerance) at baseline remained in the same glycaemic health category. Nineteen patients improved from impaired glucose tolerance to normal HbA_1c . Seven patients developed diabetes.

CONCLUSIONS

These data demonstrate that 4 years' GH replacement therapy did not adversely affect glucose homeostasis in the majority of adults with GHD.

Risk for severe hypoglycaemia with unawareness in GH-deficient patients during the insulin tolerance test

OBJECTIVE

The insulin tolerance test (ITT) has been suggested as the gold standard for diagnosing GH deficiency (GHD). The ITT is, however, potentially hazardous. Glucose monitoring during the ITT varies between centres and there is surprisingly little information on the actual level of blood glucose nadir and the duration of hypoglycaemia in patients undergoing the ITT. The aim of the present study was to closely monitor the blood glucose level and to register the presence of symptoms and signs of hypoglycaemia during the ITT.

DESIGN AND PATIENTS

Sixteen patients (seven women), aged 22-59 years were consecutively recruited for an ITT, and showed GHD (peak GH < 3 microg/l).

RESULTS

In five (31%) of the patients unawareness of hypoglycaemia was recorded, the median nadir blood glucose level was 1.4 mmol/l (range 1.1-1.9) and the duration of blood glucose < 2.2 mmol/l was 25 min (range 20-33). The remaining 11 patients were symptomatic, and tiredness (n=6) and dizziness (n=3) were the most frequent symptoms. In these symptomatic patients the median nadir blood glucose level was 1.3 mmol/l (range 1.0-1.6) and the duration of blood glucose < 2.2 mmol/l was 25 min (range 15-30).

CONCLUSIONS

In patients with GHD subjected to the ITT, symptoms of hypoglycaemia were scarce and a third showed unawareness. Close blood glucose monitoring is recommended at the ITT as low nadir blood glucose levels and long duration of hypoglycaemia may be present irrespective of symptoms of hypoglycaemia. Recommendations for intervention with intravenous glucose, at unacceptable low blood glucose levels or at prolonged hypoglycaemia, are warranted.