What is the clinical evidence from this study?

Study design: RCT. Population: Type 1 diabetes (n=36). Intervention: Premeal insulin administration vs. Postmeal insulin administration. Primary outcome: Change in myocardial microvascular blood flow (MBF) (Fold change 1.333, 95% CI 1.008-1.764, p=0.044).

What does this research mean for the field?

Premeal insulin administration lowers postprandial blood glucose and increases myocardial microvascular blood flow compared to postmeal administration in people with type 1 diabetes. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To evaluate whether the timing of prandial insulin administration influences postprandial hyperglycaemia and vascular function, specifically myocardial microvascular blood flow, in people with type 1 diabetes.

July 12, 2026DiabetologiaOpen Access

Premeal insulin administration lowers postprandial blood glucose and increases myocardial microvascular blood flow in people with type 1 diabetes: a randomised, crossover clinical trial

Q: What are the key findings of this study?

Premeal insulin administration significantly increased myocardial microvascular blood flow (fold change 1.333, p=0.044) and lowered postprandial blood glucose compared to postmeal administration in people with type 1 diabetes.

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Key result

Premeal insulin boosts myocardial microvascular blood flow ~33% vs postmeal dosing in T1D.

Fold change 1.333
95% CI 1.008-1.764
P=0.044
n=36

Why the study?

It was unknown whether prandial insulin timing affects vascular function and myocardial microvascular blood flow in people with type 1 diabetes.

Does premeal insulin administration improve myocardial microvascular blood flow in people with type 1 diabetes?

Population

18 people with type 1 diabetes (aged 18-35 years, BMI <30 kg/m2) and 18 matched controls

Comparison

Insulin injected 15 min before meal vs 15 min after meal vs no insulin in controls

Design

Randomised crossover trial with outcome assessor masking

Follow-up

2 h after meal ingestion

Authors

WHWilliam B. HortonUniversity of Virginia KAKara C. AndersonUniversity of Virginia Health System KLKaitlin M. LoveTranslational Research Institute

Discussion

Member takes

Implication

Premeal insulin timing may improve microvascular perfusion and glycemia in type 1 diabetes; extends limited RCT evidence on prandial optimization.

Key Points

To evaluate whether the timing of prandial insulin administration influences postprandial hyperglycaemia and vascular function, specifically myocardial microvascular blood flow, in people with type 1 diabetes.
In a 1:1 randomised crossover trial (ClinicalTrials.gov NCT04730882), 18 adults with type 1 diabetes (aged 18–35 years, BMI <30 kg/m²) injected prandial insulin either 15 min before or 15 min after meal intake began.
Eighteen age-, sex-, and BMI-matched control participants consumed the same meal without insulin, and outcome assessors were masked to group assignment.
Plasma glucose, insulin, and vascular function—including myocardial microvascular perfusion, aortic stiffness, and brachial artery endothelial function—were measured at baseline and 2 h after the meal.
Premeal insulin administration significantly increased myocardial microvascular blood flow (fold change 1.333, 95% CI 1.008, 1.764; p=0.044) via increased flow velocity (fold change 1.242, 95% CI 1.021, 1.512; p=0.031), while postmeal insulin did not (fold change 0.852, 95% CI 0.644, 1.127; p=0.252).
Geometric mean glucose area under the curve was significantly lower in the premeal insulin protocol compared with the postmeal insulin protocol (22,685 vs 26,006; p=0.015) in participants with type 1 diabetes.
Peak mean plasma glucose was 12.2 mmol/l in the premeal protocol versus 14.3 mmol/l in the postmeal protocol, and 7/18 participants achieved the 2 h postprandial glucose target of <10.0 mmol/l with premeal insulin versus 4/18 with postmeal insulin.

Study Design

Type

RCT (n=36)

Blinding

Single-blind

Randomization

1:1 randomised crossover

Multicenter

Structured PICO

Does premeal insulin administration improve myocardial microvascular blood flow in people with type 1 diabetes?

Population

36 young adults (18 with type 1 diabetes and 18 matched healthy controls) aged 18-35 years with BMI <30 kg/m2, evaluated in a crossover design for postprandial vascular function.

Intervention

Prandial insulin lispro injected 15 minutes before meal intake began (premeal insulin).

Comparator

Prandial insulin lispro injected 15 minutes after meal intake began (postmeal insulin). A separate healthy control group consumed the same meal but received no exogenous insulin.

Outcome

Change in myocardial microvascular blood flow (MBF) within each protocol, assessed at baseline and 2 hours after meal ingestion via contrast-enhanced ultrasound.surrogate

Main Result

Effect estimate: Fold change 1.333 (95% CI 1.008-1.764)

Absolute Event Rate: 1.333% vs 0.852%

p-value: p=0.044

Appropriately timed premeal insulin administration in type 1 diabetes lowers postprandial blood glucose and acutely increases myocardial microvascular blood flow.

Limitations

Small sample size
Single-center design

Cite This Study

Horton et al. (2026) conducted an RCT in Type 1 diabetes (n=36). Premeal insulin administration vs. Postmeal insulin administration was evaluated on Change in myocardial microvascular blood flow (MBF) (Fold change 1.333, 95% CI 1.008-1.764, p=0.044). Premeal insulin administration significantly increased myocardial microvascular blood flow (fold change 1.333, p=0.044) and lowered postprandial blood glucose compared to postmeal administration in people with type 1 diabetes.

synapsesocial.com/papers/6a5333754f7abc118adee146 https://doi.org/10.1007/s00125-026-06806-2

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Implication

Premeal insulin timing may improve microvascular perfusion and glycemia in type 1 diabetes; extends limited RCT evidence on prandial optimization.

Premeal insulin administration lowers postprandial blood glucose and increases myocardial microvascular blood flow in people with type 1 diabetes: a randomised, crossover clinical trial

Discussion

Member takes

Implication

Key Points

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Premeal insulin administration lowers postprandial blood glucose and increases myocardial microvascular blood flow in people with type 1 diabetes: a randomised, crossover clinical trial

Discussion

Member takes

Implication

Key Points

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Also Consider

Also Consider