Effect of time of day and fasting duration on measures of glycaemia: analysis from the Whitehall II Study

Abstract

Aims/hypothesis We aimed to study diurnal variation in glucose regulation by examining the effects of time of day and fasting duration on fasting plasma glucose (FPG), 2 h post-load plasma glucose (2hPG) and HbA 1c levels. Methods We analysed data from 5,978 non-diabetic white men and women from the prospective Whitehall II Study. All studied participants fasted for at least 8 h before a clinical examination, which included an OGTT and anthropometric measurements. We fitted mixed-effects models for FPG, 2hPG and HbA 1c as outcome variables, and time of day and/or fasting duration as explanatory variables. Models were adjusted for age, BMI and study phase.Results Time of day and fasting duration were associated inversely with FPG and positively with 2hPG. The mean difference between measures at 08:00 and 15:00 hours in men/women was −0.46 (95% CI −0.50, −0.42) mmol/l/−0.39 (95% CI −0.46, −0.31) mmol/l and 1.39 (95% CI 1.25, 1.52) mmol/l/1.19 (95% CI 0.96, 1.42) mmol/l for FPG and 2hPG, respectively. HbA 1c levels were independent of either time. Time of day and fasting duration were independently associated with 2hPG. In contrast, the effect of fasting duration on FPG was markedly attenuated with adjustment for time of day. Ageing, but not obesity, was associated with increased diurnal variation in glucose tolerance. Conclusions/interpretation Both time of day and fasting duration should be considered in clinical practice and epidemiological studies, since they have clinically relevant effects on FPG and 2hPG levels. As biochemically expected, HbA 1c levels are independent of time of blood sampling and fasting duration.

The Effect of Insulin Resistance on Breast Cancer Risk in Latinas of Mexican Origin

“…The literature explains that unlike HbA1c, blood glucose levels are influenced by external factors, such as caloric intake and fasting. 30,31 However, further analysis and research is needed to clarify the herein results.…”

Prospective association between late evening food consumption and risk of prediabetes and diabetes: the Whitehall II cohort study

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Effect of Prolonged Fasting Duration on 50 Gram Oral Glucose Challenge Test in the Diagnosis of Gestational Diabetes Mellitus

“…Convention-ally, it is believed that fasting duration is not important for performing 50 g GCTs, and many institutions recommend the test to be performed without restrictions on eating or drinking. Some studies have suggested that fasting duration influences the glucose level following a 50 g GCT in pregnant women [7,9,15], and that this duration (1-2 h, > 2 h) at different times of the day (morning, afternoon, or night) influences the test results [12]. Reportedly, this situation is associated with the increased secretion of insulin in the morning.…”

“…However, an abnormal 50 g GCT result does not always indicate GDM. Reportedly, fasting duration (the time since the last caloric intake) may have an effect on the plasma glucose level in pregnant women, and it may influence the gestational GCT results [7][8][9].…”