Postprandial glycaemic response and pain sensitivity in breast cancer survivors suffering from chronic pain: a double-blind, randomised controlled cross-over pilot experiment.

Introduction: The study's primary goal is to investigate differences in postprandial glycaemic response (PPGR) to beverages with varying glycaemic index (i.e. low and medium) between breast cancer survivors (BCS) with chronic pain and healthy pain-free controls (HC). The secondary goal of the study is to investigate the potential link between PPGR and pain-related outcomes in BCS with chronic pain.

Methods: In this study, 15 BCS and 15 HC were included. After 12 h of fasting, subjects were randomised between drinking a beverage made with 50 g of sucrose (medium) or isomaltulose (low) within 250 ml water. Blood glucose levels were monitored at fasting as well as at 15, 30, 45, 60, 90 and 120 min following beverage consumption. Furthermore, each participant was evaluated using several experimental pain measurements, including pressure pain thresholds (PPT), electrical detection threshold, electrical pain threshold, temporal summation and electrical offset analgesia (OA).

Results: The BCS group had significantly higher PPGR to sucrose (p = .001) than the HC group. Furthermore, when PPGR to sucrose was compared to PPGR to isomaltulose within the groups, the BCS group showed a considerably larger difference (p = .012). Additionally, correlation analyses indicated both positive and negative associations between PPGR after sucrose intake and specific pain measurements (PPT-tibialis (r = .599), OA (r_s = - .549), respectively) in BCS, and a positive association between the difference in PPGR between sucrose and isomaltulose and PPT-tibialis (r = .622).

Conclusion: These findings suggest that medium glycaemic index beverage intakes result in significantly higher blood glucose responses (i.e. PPGR) than low-glycaemic index beverage intakes in BCS. Additionally, BCS show an impaired glycaemic response to medium glycaemic index beverage intake and that the impaired glycaemic response might be related to pain sensitivity and endogenous analgesia in BCS. Furthermore, the higher glycaemic response to sucrose and greater difference in the amount of change in PPGR (when isomaltulose was substituted for sucrose) compared to HC highlight the importance of understanding how dietary choices with a lower glycaemic index can alter glycaemic regulation in BCS with chronic pain.