Feasibility and efficacy of an isocaloric high-protein vs. standard diet on insulin requirement, body weight and metabolic parameters in patients with type 2 diabetes on insulin therapy

Aims: To determine the feasibility and efficacy of a high-protein diet compared with a standard diet aiming for weight maintenance in insulin treated type-2 diabetic patients on insulin requirement, body weight and metabolic parameters over 12 weeks. Methods: In a randomized controlled trial we assigned 44 type-2 diabetic patients on insulin therapy either to high-protein or standard diet over 12 weeks. Parameters were evaluated at baseline and monthly. Results: After 12 weeks, the high protein diet significantly decreased insulin requirement (9.4±16.3 vs. +0.8±4.8 IU, mean±SD; p=0.007), fasting plasma glucose (41.7±62.5 vs. 2.1±39.0 mg dl ^{- 1}; p=0.02), body mass index (1.1±0.8 vs. 0.3±0.7 kg m ^{- 2}; p=0.003), fat-free (0.8±0.5 vs. 0.2±0.5kg; p=0.001), fat mass (2.6±1.7 vs. 0.8±1.6kg; p=0.001) and increased serum folate (4.2±8.3 vs. - 0.8±5.5 nmol l ^-1; p=0.04) compared to the standard diet. These beneficial metabolic effects are most likely related to the achieved weight loss. No significant differences between groups in renal function were observed. Conclusions: In this study we demonstrate that a high protein diet with emphasis on plant source protein vs. a standard diet is feasible in insulin-treated type-2 diabetic patients and reduces insulin requirement and body weight and improves metabolic parameters up to 12 weeks. A high protein diet can thus be considered as an appropriate diet choice for type-2 diabetic patients.