Continuous Glucose Measurements Using Telemetry in Male and Female Dahl Salt‐Sensitive Rats (DSS) on a High‐Fat Diet

Abstract

The HD‐XG glucose telemetry implant from DSI provides the ability to obtain continuous, real‐time, blood glucose measurements in rodents. The goal of the current study was to compare spot blood glucose measurements with values obtained using telemetry in male and female DSS. Male and female rats were implanted with glucose telemeters at 11 weeks of age, and allowed 1 week to recover before being placed on receivers. Rats were maintained on a normal‐salt, normal‐fat (NF; 16% caloric intake from fat) diet for 1 week and then were switched to a high‐fat diet (HF; 65% caloric intake from fat) for 4 weeks (n=4–5/group sex). Additional rats without telemeter implants were maintained on normal‐salt, normal‐fat diet for the duration of the experiment. All rats gained weight over the 4 week treatment period, however, rats of both sexes on a HF diet exhibited a significantly greater increase in body weight compared to rats on NF (males: 15±1% on NF vs. 22±2% on HF, p<0.05; females: 12±1% on NF vs. 18±2% on HF, p<0.05). There was not a sex difference in weight gain in response to HF diet. Mean absolute relative differences in blood glucose as measured by the HD‐XG compared to spot glucose ranged from 0.1% up to 4.8% in males and 0.7% up to 8.9% in females, indicating that the 2 measurements were always within 10% of one another. Baseline blood glucose levels in male and female DSS measured by HD‐XG were comparable (109±2 vs. 111±2 mg/dL, respectively). HF diet for 4 weeks did not significantly alter blood glucose levels in either sex (male: 106±3 mg/dL; female: 104±4 mg/dL). Additionally, average weekly glucose for both sexes were statistically identical whether analyzed over 24 hour periods or limited to only the light or dark periods. From this study we can conclude the following: 1) glucose telemeters are a reliable methods to obtain continuous measurements of blood glucose in male and female rats, 2) there are no sex differences in blood glucose following a 4 week HF diet in DSS, and 3) DSS are able to tolerate a HF diet with minimal alterations in body weight or blood glucose.