Effects of a Mediterranean-style diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetes: a randomized trial

Ann Intern Med. 2009 Sep 1;151(5):306-14. doi: 10.7326/0003-4819-151-5-200909010-00004.


Background: Low-carbohydrate and low-fat calorie-restricted diets are recommended for weight loss in overweight and obese people with type 2 diabetes.

Objective: To compare the effects of a low-carbohydrate Mediterranean-style or a low-fat diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetes.

Design: Single-center, randomized trial. Randomization was computer-generated and unstratified. Allocation was concealed in sealed study folders held in a central, secure location until participants gave informed consent. Participants and investigators were aware of treatment assignment, and assessors of the primary outcome were blinded.

Setting: Teaching hospital in Naples, Italy.

Patients: 215 overweight people with newly diagnosed type 2 diabetes who were never treated with antihyperglycemic drugs and had hemoglobin A(1c) (HbA(1c)) levels less than 11%.

Intervention: Mediterranean-style diet (<50% of daily calories from carbohydrates) (n = 108) or a low-fat diet (<30% of daily calories from fat) (n = 107).

Measurements: Start of antihyperglycemic drug therapy, defined by protocol as indicated for follow-up HbA(1c) level greater than 7% (primary outcome), and changes in weight, glycemic control, and coronary risk factors (secondary outcomes).

Results: After 4 years, 44% of patients in the Mediterranean-style diet group and 70% in the low-fat diet group required treatment (absolute difference, -26.0 percentage points [95% CI, -31.1 to -20.1 percentage points]; hazard ratio, 0.63 [CI, 0.51 to 0.86]; hazard ratio adjusted for weight change, 0.70 [CI, 0.59 to 0.90]; P < 0.001). Participants assigned to the Mediterranean-style diet lost more weight and experienced greater improvements in some glycemic control and coronary risk measures than did those assigned to the low-fat diet.

Limitations: Investigators responsible for initiating drug therapy were not blinded to treatment assignment. Dietary intake was self-reported.

Conclusion: Compared with a low-fat diet, a low-carbohydrate, Mediterranean-style diet led to more favorable changes in glycemic control and coronary risk factors and delayed the need for antihyperglycemic drug therapy in overweight patients with newly diagnosed type 2 diabetes.

Primary funding source: Second University of Naples.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Blood Glucose / metabolism
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / complications
  • Diabetes Mellitus, Type 2 / diet therapy*
  • Diabetes Mellitus, Type 2 / drug therapy
  • Diet, Carbohydrate-Restricted*
  • Diet, Fat-Restricted
  • Diet, Mediterranean*
  • Exercise
  • Female
  • Follow-Up Studies
  • Glycated Hemoglobin / metabolism
  • Humans
  • Hypoglycemic Agents / therapeutic use
  • Male
  • Middle Aged
  • Obesity / complications
  • Obesity / diet therapy
  • Overweight / complications
  • Overweight / diet therapy*
  • Risk Factors
  • Weight Loss


  • Blood Glucose
  • Glycated Hemoglobin A
  • Hypoglycemic Agents