Six-Month Periodic Fasting in Patients With Type 2 Diabetes and Diabetic Nephropathy: A Proof-of-Concept Study

Abstract

Context: Novel fasting interventions have gained scientific and public attention. Periodic fasting has emerged as a dietary modification promoting beneficial effects on metabolic syndrome.

Objective: Assess whether periodic fasting reduces albuminuria and activates nephropathy-driven pathways.

Design/participants: Proof-of-concept study where individuals with type 2 diabetes (n = 40) and increased albumin-to-creatinine ratio (ACR) were randomly assigned to receive a monthly fasting-mimicking diet (FMD) or a Mediterranean diet for 6 months with 3-month follow-up.

Main outcomes measures: Change in ACR was assessed by analysis of covariance adjusted for age, sex, weight loss, and baseline value. Prespecified subgroup analysis for patients with micro- vs macroalbuminuria at baseline was performed. Change in homeostatic model assessment for insulin resistance (HOMA-IR), circulating markers of dicarbonyl detoxification (methylglyoxal-derived hydroimidazolone 1, glyoxalase-1, and hydroxyacetone), DNA-damage/repair (phosphorylated histone H2AX), lipid oxidation (acylcarnitines), and senescence (soluble urokinase plasminogen activator receptor) were assessed as exploratory endpoints.

Results: FMD was well tolerated with 71% to 95% of the participants reporting no adverse effects. After 6 months, change in ACR was comparable between study groups [110.3 (99.2, 121.5) mg/g; P = 0.45]. FMD led to a reduction of ACR in patients with microalbuminuria levels at baseline [-30.3 (-35.7, -24.9) mg/g; P ≤ 0.05] but not in those with macroalbuminuria [434.0 (404.7, 463.4) mg/g; P = 0.23]. FMD reduced HOMA-IR [-3.8 (-5.6, -2.0); P ≤ 0.05] and soluble urokinase plasminogen activator receptor [-156.6 (-172.9, -140.4) pg/mL; P ≤ 0.05], while no change was observed in markers of dicarbonyl detoxification or DNA-damage/repair. Change in acylcarnitines was related to patient responsiveness to ACR improvement. At follow-up only HOMA-IR reduction [-1.9 (-3.7, -0.1), P ≤ 0.05]) was sustained.

Conclusions: Improvement of microalbuminuria and of markers of insulin resistance, lipid oxidation, and senescence suggest the potential beneficial effects of periodic fasting in type 2 diabetes.

Keywords: diabetic nephropathy; dicarbonyl detoxification; insulin resistance; lipid oxidation; periodic fasting; senescence.

Figure 1.

Study design (A) and CONSORT flow diagram (B). Abbreviations: AL, ad libitum; FMD, fasting-mimicking diet; M-Diet, Mediterranean diet; rV3, visit at refeeding 1 week after the third diet cycle; rV6, visit at refeeding one week after the sixth diet cycle; V0, visit at baseline; V1, visit after the first diet cycle; V2, visit after the second diet cycle; V3, visit after the third diet cycle; V4, visit after the fourth diet cycle; V5, visit after the fifth diet cycle; V6, visit after the sixth diet cycle; V7, follow-up visit 3 months after study completion.

Figure 2.

Effects of fasting on microalbuminuria (A), HOMA-IR (B), MG-H1 (C), suPAR (D), and blood ketone bodies (E) after 3 months, after 6 months, and at follow-up. Data are shown as mean ± SE of the mean of unadjusted values of parameter. P-values indicate significance level of intervention effect on change compared to baseline and are based on M-Diet–corrected analysis of covariance with adjustment for age, sex, and weight loss. ***P ≤ 0.001, **P ≤ 0.01, *P ≤ 0.05. Abbreviations: FMD, fasting-mimicking diet; HOMA-IR, homeostatic model assessment of insulin resistance; M-Diet, Mediterranean diet; MG-H1, methylglyoxal-derived hydroimidazolone 1; suPAR, soluble urokinase plasminogen activator receptor.

Figure 3.

Plasma methylglyoxal level (A), glyoxalase 1 activity in white blood cells (B), phosphorylated glyoxalase-1 expression in white blood cells (C), hydroxyacetone concentration in red blood cells (D), yH2Ax in white blood cells (E), and comet assay with white blood cells (F). Data are shown as mean ± SE of the mean of unadjusted values of parameter. Total Glo-1 immunoblotting is a rehybridization of the pGlo-1 in (C). Representative participants were analyzed in (A) M-Diet, n = 11, FMD, n = 11; (B) M-Diet n = 11, FMD n = 12; (C) M-Diet n = 6, FMD n = 12; (D) M-Diet n = 19, FMD n = 21; (E) M-Diet n = 6, FMD n = 9; and (F) M-Diet n = 6, FMD n = 12. Abbreviations: FMD, fasting-mimicking diet; Glo-1, glyoxalase 1; MCHC, mean corpuscular hemoglobin concentration M-Diet, Mediterranean diet; MG, methylglyoxal; pGlo-1, phosphorylated glyoxalase 1; RBC, red blood cells; WBC, white blood cell; yH2Ax phosphorylated histone H2AX.

Figure 4.

Effects of fasting on acylcarnitines after 3 months, after 6 months, and at follow-up. Heat map analysis of acylcarnitine profile reveal differences between the study groups dependent on change in albuminuria. Patients in the intervention group that show at least a 30% decrease in albuminuria level after 3 and after 6 diet cycles compared to the respective baseline are referred as “responders,” while the rest are referred as “nonresponders.” Groups in the analysis: M-Diet, nonresponders, and responders. Each row displays a metabolite and each column represent the absolute change of the annotated metabolite after 3 diet cycles (left panel), after 6 diet cycles (middle panel), and at follow-up (right panel) compared to baseline of the respective group and is displayed as range-scaled Z-score. Metabolites increased are displayed in red while metabolites decreased are displayed in blue. Abbreviations: 3HMG, 3-hydroxy-3-methylglutarylcarnitin; C0, carnitine; C2, acetylcarnitine; C3, propionylcarnitine; C4, butyrylcarnitine; isobutyrylcarnitine; C5, valerylcarnitine, isovalerylcarnitine, methylbutyrylcarnitine; C5_1, tiglylcarnitine, methylcrotonylcarnitine; C6, hexanoylcarnitine; C5OH + HMB, hydroxyvalerylcarnitine + 2-OH-3-methyl-butyrylcarnitin; C8, octanoylcarnitine; C8_1, octenoylcarnitine, C10, decanoylcarnitine; C10_1, decenoylcarnitine; C12, dodecanoylcarnitine; C14, tetradecanoylcarnitine; C14_1, tetradecenoylcarnitine; C14OH, hydroxytetradecanoylcarnitin; C16, hexadecanoylcarnitine; C16_1, hexadecenoylcarnitine; C16_1OH, hydroxyhexadecenoylcarnitine; C16OH, hydroxyhexadecanoylcarnitine; C18, octadecanoylcarnitine; C18_1, octadecenoylcarnitine; C18_1OH, hydroxyoctadecenoylcarnitine; C18_2, octadecadienylcarnitine; C18OH, hydroxyoctadecanoylcarnitin; glut glutarylcarnitine; M-Diet, Mediterranean diet; MeGlut, methylglutarylcarnitine; MMA, methylmalonylcarnitin, Non-Resp., nonresponders; Resp., responders.

Figure 5.

Subject self-reported adverse effects based on Common Terminology Criteria for Adverse Events (A). Hypoglycemic and hyperglycemic episodes in both study groups reported during the study (B). 1 = mild, 2 = moderate, 3 = severe, 4 = life-threatening, 5 = death. Percentage of subjects reporting no adverse effect (grade 0), grade 1, or grade 2 adverse effects; grades 3 to 5 were not reported. Abbreviations: FMD, fasting-mimicking diet; M-Diet, Mediterranean diet.

Figure 6.

Change of antihyperglycemic (A) and antihypertensive medication (B) after 3 diet cycles (V3) and after 6 diet cycles (V6). Abbreviations: FMD, fasting-mimicking diet; M-Diet, Mediterranean diet.