High-Dose, Diazoxide-Mediated Insulin Suppression Boosts Weight Loss Induced by Lifestyle Intervention

CONTEXT

Obesity-related hyperinsulinism may impede lifestyle-initiated weight loss.

OBJECTIVE

Proof-of-concept study to investigate the amplifying effects of diazoxide (DZX)-mediated insulin suppression on lifestyle-induced weight loss in nondiabetic, hyperinsulinemic, obese men.

DESIGN

Twelve-month study comprising an initial 6-month, double-blind trial, followed by a partially de-blinded 6-month extension in men with obesity with a body mass index of 30 to 37.5 kg/m2 and a fasting serum C-peptide level >1.00 nM. Patients were randomized into three treatment groups: DZX + placebo (DZX + PL), DZX + metformin (DZX + MTF), and double PL (PL + PL).

RESULTS

At 6 months, DZX treatment was associated with a 6.1-kg PL-subtracted decline in fat mass (FM), and at 12 months, FM had decreased by a total of 15.7 ± 2.5 kg. Twelve months of DZX treatment was also associated with a significant decline in systolic (-6.6%) and diastolic (-8.6%) blood pressure and low-density lipoprotein-cholesterol (-18%) and triglycerides (-43%) and a 39% rise in high-density lipoprotein-cholesterol. These effects were achieved at the cost of a small rise in fasting glucose (95% CI: 0.2 to 1.0 mM) and hemoglobin A1c (95% CI: -0.08% to 0.44%). There were no differences between DZX monotherapy and the combination of DZX + MTF.

CONCLUSION

High-dose DZX treatment of 1 year resulted in a substantial decrease in FM, blood pressure, and lipid levels at the cost of a small rise in blood glucose levels.

Effects of Diazoxide-Mediated Insulin Suppression on Glucose and Lipid Metabolism in Nondiabetic Obese Men

CONTEXT

It has been suggested that stimulation of lipolysis by diazoxide (DZX)-mediated insulin suppression may be useful in treating obesity. However, the optimal dose to promote lipolysis without causing hyperglycemia is unknown.

OBJECTIVE

To assess the effects of DZX in nondiabetic obese men on lipid and glucose metabolism.

DESIGN

Double-blind, placebo (PL)-controlled, 6-month trial in men with a body mass index of 30 to 37.5 kg/m2 treated with a combination of caloric restriction, a standardized exercise program, and DZX or PL dose escalation.

RESULTS

The mean maximal tolerated dose of DZX was 422 ± 44 mg/d (range, 200 to 700 mg/d). Dose-limiting events were edema (n = 11), hyperglycemia (n = 6), and nausea (n = 2). After dose reduction to a level free of clinical side effects, DZX treatment was associated with a markedly greater decrease in fasting insulin levels than PL (-72.3 ± 3.5% vs -23.0 ± 12.6%; P < 0.001) and a significant improvement of blood pressure and plasma lipid levels. The decline in insulin levels occurred at the cost of a small increase in plasma glucose (0.6 ± 0.2 mmol/L vs -0.1 ± 0.1 mmol/L; P = 0.04) and hemoglobin A1C (0.2 ± 0.1% vs 0.0 ± 0.1%; P = 0.17).

CONCLUSION

In nondiabetic obese men, insulin levels can be reduced up to 70% without major metabolic side effects. The marked intersubject variation in maximal tolerated dose indicates that DZX dose titration needs to be individualized.

Gonadal status and outcome of bariatric surgery in obese men

BACKGROUND

Obesity-related hypogonadotrophic hypogonadism (OrHH) occurs in over 40% of morbidly obese men. Obesity-related hypogonadotrophic hypogonadism may reduce the beneficial effects of bariatric surgery.

OBJECTIVE

To assess the impact of OrHH on the outcome of bariatric surgery in men.

PATIENTS AND METHODS

Observational study with measurement of serum gonadal hormones, and assessment of body composition, glucose, lipid and bone metabolism during the first year after bariatric surgery in 13 men with OrHH (free testosterone (free T) <225 pmol/l) and 11 age-matched eugonadal morbidly obese men (free T > 225 pmol/l).

RESULTS

Serum free T was inversely related to body weight (R = -0·65, P < 0·0001) and rose gradually after bariatric surgery, in eugonadal as well as in OrHH men, by 30 pmol/l for every 10 kg loss of weight. In three patients, serum free T remained within the hypogonadal range despite substantial weight loss. Gonadal hormone status prior to surgery did not affect the 1-year outcome of surgery.

CONCLUSION

Obesity-related hypogonadotrophic hypogonadism is a reversible condition in the majority of obese men. It does not reduce the efficacy of bariatric surgery. Preoperative weight-adjusted normal values are recommended to avoid an incorrect diagnosis of hypogonadism in obese men.

Somatic and psychological effects of low-dose aromatase inhibition in men with obesity-related hypogonadotropic hypotestosteronemia

INTRODUCTION

Reduced testosterone levels are frequently observed in obese men. Increased aromatase activity may be an etiological factor.

OBJECTIVE

In this study, we evaluate the clinical effects of aromatase inhibition in obesity-related hypogonadotropic hypotestosteronemia (OrHH).

METHODS

Double-blind, placebo-controlled, 6-month trial in 42 obese men with a BMI >35 kg/m(2), and a serum total testosterone <10 nmol/l. All patients started on one tablet of 2.5 mg/week, with subsequent dose escalation every month until a serum total testosterone of 20 nmol/l was reached.

ENDPOINTS

Psychological function, body composition, exercise capacity, and glucose, lipid, and bone metabolism.

RESULTS

Thirty-nine patients completed the study according to protocol. Letrozole decreased serum estradiol from 119.1±10.1 to 59.2±6.1 pmol/l (P<0.001), and increased serum LH from 3.3±0.3 to 8.8±0.9 U/l (P<0.0001) and serum total testosterone from 8.6±0.7 to 21.5±1.3 nmol/l (P<0.0001). Significant effects on the predefined endpoints were not observed.

CONCLUSION

Despite a marked rise in serum testosterone, low-dose aromatase inhibition had no somatic or psychological effects in men with OrHH.

Weight loss in obese men by caloric restriction and high-dose diazoxide-mediated insulin suppression

OBJECTIVE

To examine the concept whether high-dose diazoxide (DZX)-mediated insulin suppression, in combination with moderate caloric restriction and increased physical activity, can establish a weight loss of at least 15% in obese hyperinsulinaemic men.

DESIGN

Open, uncontrolled, 6-month pilot study. Energy intake was reduced by 30%, and walking for at least 30 min a day was strongly recommended. DZX treatment was started at 50 mg t.i.d. and increased by 50 mg per dose every 4 weeks to a maximum of 300 mg t.i.d., unless hyperglycaemia or other side-effects occurred.

SUBJECTS AND METHODS

Eighteen obese hyperinsulinaemic men with a body mass index of 30-35 kg/m(2). Measurements included body weight, body composition, blood pressure, glycaemic control, insulin response, adiponectin and serum lipids.

RESULTS

Body weight decreased by 9.4 kg (95% CI: 5.6-13.2 kg, p < 0.001), waist circumference reduced by 9.2 cm (95% CI: 5.3-12.9 cm, p < 0.001) and total body fat mass decreased by 23.3% (95% CI: 13.7-32.9%, p < 0.001), without a concomitant change in soft tissue lean body mass or bone mass. Fat loss was inversely related to fasting insulin levels achieved at 6 months (r = -0.76, p < 0.002). Diastolic blood pressure decreased by 10.9 mmHg (95% CI: 6.5-15.4 mmHg, p < 0.002). Fasting and postmeal peak insulin levels were reduced by about 65% (p < 0.001) and decreased to the normal range for non-obese men. Fasting and postmeal peak glucose levels increased by 0.8 +/- 0.3 mmol/l (p = 0.01) and 1.4 +/- 0.7 mmol/l (p = 0.06) respectively. Haemoglobin A1c rose by 0.5% to 5.9 +/- 0.2%.

CONCLUSION

High-dose DZX-mediated insulin suppression, in combination with moderate caloric restriction and lifestyle advice, is associated with a clinically relevant degree of weight reduction. A more extensive exploration is warranted to optimize this mode of treatment and to further clarify its risks and benefits.

Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism

OBJECTIVE

Isolated hypogonadotropic hypogonadism (IHH) is frequently observed in severely obese men, probably as a result of increased estradiol (E(2)) production and E(2)-mediated negative feedback on pituitary LH secretion. Aromatase inhibitors can reverse this process. This study evaluates whether letrozole once a week can normalize serum testosterone in severely obese men and maintain its long term effect.

DESIGN

Open, uncontrolled 6-month pilot study in 12 severely obese men (body mass index>35.0 kg/m(2)) with obesity-related IHH and free testosterone levels <225 pmol/l, treated with 2.5 mg letrozole once a week for 6 months.

RESULTS

Six weeks of treatment reduced total E(2) from 123+/-11 to 58+/-7 pmol/l (P<0.001, mean+/-s.e.m.), and increased serum LH from 4.4+/-0.6 to 11.1+/-1.5 U/l (P<0.001). Total testosterone rose from 5.9+/-0.5 to 19.6+/-1.4 nmol/l (P<0.001), and free testosterone from 163+/-13 to 604+/-50 pmol/l (P<0.001). Total testosterone rose to within the normal range in all subjects, whereas free testosterone rose to supraphysiological levels in 7 out of 12 men. The testosterone and E(2) levels were stable throughout the week and during the 6-month treatment period.

CONCLUSION

Letrozole 2.5 mg once a week produced a sustained normalization of serum total testosterone in obese men with IHH. However, free testosterone frequently rose to supraphysiological levels. Therefore, a starting dose <2.5 mg once a week is recommended.

High prevalence of hypogonadotropic hypogonadism in men referred for obesity treatment

BACKGROUND

Obesity can be associated with biochemical evidence of isolated hypogonadotropic hypogonadism (IHH) in men. Prevalence and severity of IHH in obese men are not exactly known.

OBJECTIVE

To assess the prevalence of IHH in obese men.

DESIGN AND SUBJECTS

Cross-sectional study of 160 obese men, BMI >30 kg/m2, who applied for medical or surgical treatment of obesity in a general teaching hospital.

MAIN OUTCOME MEASURES

Total and calculated free testosterone (TT and FT) in relation to body mass index (BMI).

RESULTS

Mean age of the study population was 43.3 +/- 0.8 years (mean +/- SEM), BMI ranged from 30.0 to 65.7 kg/m2. TT and FT levels were inversely related to BMI (-0.48, p<0.0001). Total testosterone was subnormal in 57.5% and free testosterone in 35.6% of the subjects. The group of men with IHH was more obese, had higher Hba IC levels and had a 2.6 higher risk for cardiovascular disease. Decreased libido and erectile dysfunction were 7.1 and 6.7 times as common in IHH than in eugonadal obese men.

CONCLUSION

Reduced T levels, well into the hypogonadal range, are common in male obesity. Assessment of its clinical implications, and a search for the best mode of treatment are warranted.