JMIR Publications

ABSTRACT

Background:

Glucose-guided eating (GGE) improves metabolic markers of chronic disease risk, including insulin resistance, among adults without diabetes. GGE is a timed eating paradigm that relies on experiencing feelings of (physical) hunger and having a preprandial glucose below a threshold that has been computed from 2 consecutive morning fasting glucose levels, which is often experienced in persons with diabetes. The dawn phenomenon (DP) is the increase in blood glucose levels between the nocturnal nadir and early morning. Computing GGE thresholds without considering the effect of DP on morning preprandial glucose could cause GGE to be less effective or unfeasible for those with diabetes.

Objective:

To quantify the incidence and day-to-day variability in the magnitude of DP and examine its effect on morning preprandial glucose levels as a preliminary test of the feasibility of GGE in adults with type 2 diabetes (T2DM).

Methods:

Study participants wore a single, blinded Dexcom G6 Pro continuous glucose monitoring (CGM) system. The timing of meals and any overnight eating was reported using daily surveys over the study duration. DP was expressed as a dichotomous variable at the day level (DP day vs. non-DP day) and as a continuous variable reflecting the percent of days DP was experienced on a valid day. A valid day was defined as having no reported overnight eating (12am-6am). DP was defined as a change of ≥ 20 mg/dL in CGM-measured glucose from the nocturnal nadir to the morning preprandial level. Using multi-level modeling, we examined the between- and within-person effects of DP on morning preprandial glucose and the effect of evening eating times on DP.

Results:

22 men and women (59% female) with noninsulin-treated T2DM wore a CGM for an average of 10.5 (SD 1.1) days. 95% of participants experienced DP at least one day with an average of 51% of days (SD 27.2, range 0–100%). People who experience DP more frequently had a morning preprandial glucose 54.1 mg/dL (95% CI 17.0, 83.9) higher than those who experienced DP less frequently (p = <.0001). Within person, morning preprandial glucose was 12.1 mg/dL (95% CI 6.3, 17.8) higher on a DP day vs. a non-DP day (p = .008). There was no effect of evening eating time on DP.

Conclusions:

DP was experienced by most of the studied sample regardless of the timing of evening meals. The within-person effect of DP on morning preprandial glucose was meaningful and should be considered when determining a feasible GGE threshold.