Calorie Restriction and Kidney Outcomes in Obese Type 2 Diabetes Patients

Among obese patients with type 2 diabetes, hyperfiltration is a risk factor for accelerated decline in glomerular filtration rate and is ameliorated by calorie restriction. Pierro Ruggenenti, MD, and colleagues conducted a study to examine whether amelioration of hyperfiltration via calorie restriction could translate into slower long-term decline in GFR in that patient population.

Results of the academic, single-center, parallel-group, prospective, randomized, open-label, blinded end point trial were reported in online in Diabetes Research and Clinical Practice [doi.org/10.1016.j.diabres.2022.1098094].

Inclusion criteria were patients >40 years of age with type 2 diabetes, body mass index (BMI) ≥27 kg/m², creatinine <1.2 mg/dL, and albuminuria ≤300 mg/24 hours. Participants were randomized 1:1 to 2-year 25% calorie restriction (n=53) or standard diet (SD, n=50). The primary outcome of interest was 6-month measured GFR. Analyses were by modified intention-to-treat.

At 6 months, GFR decrease in the calorie restriction group was 5.16 mL/min (P=.001) compared with 0.98 mL/min in the SD group (P=.497). The between group difference was statistically significant (P=.044). From 6 to 24 months, the decline in GFR was significant in the SD group (P<.01) but not in the calorie restriction group (P=.075). However, the between group difference did not reach statistical significance.

In the calorie restriction group, there were decreases in body weight, BMI, waist circumference, systolic blood pressure, hemoglobin A1c, blood glucose, and serum triglycerides, and increases in ApoA-1 concentration. There were no changes observed with standard diet. The between group differences were significant. Calorie restriction was well tolerated

In summary, the authors said, “In obese type 2 diabetic patients, calorie restriction ameliorated glomerular hyperfiltration and several cardiovascular risk factors, and blunted long-term GFR decline.”