MTNR1B genotype and effects of carbohydrate quantity and dietary glycaemic index on glycaemic response to an oral glucose load: the OmniCarb trial.
Study Goal
The researchers aimed to determine whether the MTNR1B-rs10830963 genetic variant influences glycemic responses to different carbohydrate quantities and dietary glycemic index (GI) levels.
Results Summary
Carrying the risk G allele of MTNR1B-rs10830963 was associated with greater glycemic responses after consuming a high-carbohydrate/high-GI diet, while reducing GI in high-carbohydrate diets decreased post-OGTT glucose concentrations, particularly in G-allele carriers.
Population
150 participants in a randomized crossover-controlled feeding trial.
Effective Dosage
Not specified
Duration
5 weeks per diet intervention
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
high-carbohydrate/high-GI diet | increase | AUC of glucose during 2 h OGTT | risk G allele (CG/GG vs CC genotype) carriers of MTNR1B-rs10830963 | β 134.32 [SE 45.69] mmol/l × min | was associated with the largest AUC of glucose during 2 h OGTT | #1 |
high-carbohydrate/high-GI diet | increase | glucose during 0-60 min | risk G-allele carriers | β 1.26 [0.47] mmol/l | showed greater increment of glucose during 0-60 min | #2 |
high-carbohydrate/high-GI diet | increase | glucose during 0-90 min | risk G-allele carriers | β 1.10 [0.50] mmol/l | showed greater increment of glucose during 0-90 min | #3 |
reducing GI levels at high carbohydrate content | decrease | 60 min post-OGTT glucose | - | mean -0.67 [95% CI: -1.18, -0.17] mmol/l | decreased 60 min post-OGTT glucose | #4 |
reducing GI levels at high carbohydrate content | decrease | increment of glucose during 0-60 min | - | mean -1.00 [95% CI: -1.67, -0.33] mmol/l | decreased the increment of glucose during 0-60 min | #5 |
reducing GI levels at high carbohydrate content | decrease | increment of glucose during 0-90 min | risk G-allele carriers | - | decreased the increment of glucose during 0-90 min | #6 |
AIMS/HYPOTHESIS: A type 2 diabetes-risk-increasing variant, MTNR1B (melatonin receptor 1B) rs10830963, regulates the circadian function and may influence the variability in metabolic responses to dietary carbohydrates. We investigated whether the effects of carbohydrate quantity and dietary glycaemic index (GI) on glycaemic response during OGTTs varied by the risk G allele of MTNR1B-rs10830963. METHODS: This study included participants (n=150) of a randomised crossover-controlled feeding trial of four diets with high/low GI levels and high/low carbohydrate content for 5 weeks. The MTNR1B-rs10830963 (C/G) variant was genotyped. Glucose response during 2 h OGTT was measured at baseline and the end of each diet intervention. RESULTS: Among the four study diets, carrying the risk G allele (CG/GG vs CC genotype) of MTNR1B-rs10830963 was associated with the largest AUC of glucose during 2 h OGTT after consuming a high-carbohydrate/high-GI diet (β 134.32 [SE 45.69] mmol/l × min; p=0.004). The risk G-allele carriers showed greater increment of glucose during 0-60 min (β 1.26 [0.47] mmol/l; p=0.008) or 0-90 min (β 1.10 [0.50] mmol/l; p=0.028) after the high-carbohydrate/high-GI diet intervention, but not after consuming the other three diets. At high carbohydrate content, reducing GI levels decreased 60 min post-OGTT glucose (mean -0.67 [95% CI: -1.18, -0.17] mmol/l) and the increment of glucose during 0-60 min (mean -1.00 [95% CI: -1.67, -0.33] mmol/l) and 0-90 min, particularly in the risk G-allele carriers (p CONCLUSIONS/INTERPRETATION: Our study shows that carrying the risk G allele of MTNR1B-rs10830963 is associated with greater glycaemic responses after consuming a diet with high carbohydrates and high GI levels. Reducing GI in a high-carbohydrate diet may decrease post-OGTT glucose concentrations among the risk G-allele carriers.