A Trial Evaluating the Effects of a One-year Lifestyle Intervention in Obese Patients With Type 2 Diabetes

Diabetic patients with uncontrolled disease are often characterized by increased energy expenditure and could thus present a high resting metabolic rate (RMR). Lifestyle interventions aimed at improving glucose control in these patients may lead to reductions of futile pathways, resulting in lower rates of energy expenditure, and paradoxically to making it more difficult to lose weight. However, only few studies investigated how exercise could influence patients' RMR and results are still not unanimous. In this study, we aim to investigate the effects on metabolic health of a combined dietary intervention and 12-week exercise training in obese adults with type 2 diabetes.

Although a number of exercise training interventions have been proposed to type 2 diabetes patients, the current clinical practice demonstrates that most patients are still sedentary and with excess body weight. A negative balance between energy intake and energy expenditure is crucial to reduce excess body weight. However, diabetic patients with uncontrolled disease are often characterized by increased energy expenditure and could thus present a high resting metabolic rate (RMR). Lifestyle interventions aimed at improving glucose control in these patients may lead to reductions of futile pathways, resulting in lower rates of energy expenditure, and paradoxically to making it more difficult to lose weight. However, no robust evidence has been collected on this issue, and the few studies that investigated how exercise could influence patients' RMR have not shown unanimous results, especially concerning combined dietary and physical activity interventions.

This open-label randomized trial in obese adults with type 2 diabetes aims to investigate the effects of a 1-year caloric restriction and 12-week exercise training intervention on metabolic health, RMR and VO2max.

In particular, eligible type 2 diabetes patients of our clinic will be invited to participate in a short lifestyle intervention (LSI). LSI will consist of four weekly group-led lessons lasting 60-90 minutes in which specialized professionals will educate patients on specific dietary and physical activity recommendations for improving health and metabolic control.

After this month, patients will be randomly assigned either to: 1) 1-year caloric restriction with an immediate start of 12-week supervised structured exercise training (SSET) (Early-SSET intervention), followed by no exercise at health centers for 3 months; or: 2) 1-year caloric restriction with no exercise at health centers for 3 months and then a 12-week SSET from month 4 to month 6 (Late-SSET intervention). During the last 6 months participants' activity will be unrestricted.

Type 2 diabetic and obese adult volunteers will be recruited and screened through medical history, physical examination and biochemical analyses.

Eligibility Criteria:
Inclusion Criteria:

* Signed informed consent
* age 30 to 64 years
* less than 60 min aerobic exercise/week
* absence of acute diseases
* no current treatment with insulin or sulfonylureas

Exclusion Criteria:

* Body mass index (BMI)\<28
* HbA1c\<6%
* Recent acute diseases, severe infections, trauma or surgery
* Uncontrolled hypertension or hyperglycemia
* Evidence of advanced cardiovascular, renal or hepatic diseases
* Contraindication to exercise
* Body weight change of more than 3% within the last 6 months
* Medication changes within the last 3 months