Cranberry Proanthocyanidins and Lactobacilli for Recurrent UTI Prevention in Type 2 Diabetes

Overview

The purpose of this prospective, single-arm feasibility study was to evaluate the operational feasibility, tolerability, safety, and exploratory clinical outcomes of an oral supplement combining standardized cranberry proanthocyanidins (PACs) and a multi-strain Lactobacillus formulation in women with type 2 diabetes mellitus and a documented history of recurrent urinary tract infections (rUTIs). Participants received a 60-day active intervention consisting of a combined capsule taken twice daily, followed by a 120-day observation period without study intervention, for a total follow-up duration of 180 days. Primary feasibility outcomes included screening and enrollment metrics, retention rate at day 180, and tolerability/adverse event rates. Exploratory endpoints included the incidence of microbiologically confirmed symptomatic UTIs and changes in antibiotic prescription rates compared with pre-enrollment history.

Women with type 2 diabetes mellitus (T2DM) are disproportionately affected by recurrent urinary tract infections due to glucosuria, impaired innate immune defenses, and urogenital dysbiosis, which is often compounded by the use of sodium-glucose cotransporter-2 (SGLT2) inhibitors. This prospective, open-label, single-arm feasibility study was conducted at the National Institute of Endocrinology in Tbilisi, Georgia. Eligible participants were women aged 40 to 75 years with established T2DM (HbA1c 6.5%-10.0%) and a confirmed history of recurrent UTIs (defined as \>=2 episodes in the prior 12 months or \>=1 in the prior 6 months) without active infection at enrollment. The study protocol comprised: 1. Screening window: up to 14 days to confirm eligibility and baseline stability. 2. Active intervention phase: 60 consecutive days of oral supplementation with a commercial capsule containing 72 mg of standardized cranberry PACs and 2x10\^9 CFU of a multi-strain Lactobacillus formulation (L. rhamnosus, L. acidophilus, L. casei) taken twice daily with meals (total 144 mg PACs daily). 3. Observation phase: 120 days of prospective follow-up without study supplementation. Standard glucose-lowering therapies (including metformin and SGLT2 inhibitors) were maintained unchanged throughout the 180-day study. The study was designed to generate operational, safety, and preliminary signal data to inform the sample size calculation and methodological design of a future randomized, double-blind, placebo-controlled clinical trial.