Postprandial capillary–venous glucose gradient in Type 1 diabetes: magnitude and clinical associations in a real world setting

AIMS: To determine the magnitude of the peripheral glucose gradient in patients with Type 1 diabetes in a real world setting and to explore its relationship with insulin dose and macronutrient intake. METHODS: All patients used mealtime analogue insulin. The glucose gradient was assessed using antecubital fossa venous and finger‐stick capillary samples, collected concurrently at room temperature. Baseline sampling occurred before the administration of an insulin dose and breakfast of the patient's choosing. Breakfast was consumed an average of 15 min after baseline. The macronutrient content of breakfast was documented. Sampling was repeated 1 and 2 h after baseline. RESULTS: The mean (95% CI) plasma capillary–venous glucose gradient values for 43 patients were: pre‐breakfast, 0.21 (0.08–0.34) mmol/l; 1 h after baseline, 0.87 (0.66–1.07) mmol/l; and 2 h after baseline, 0.52 (0.33–0.71) mmol/l. Glucose gradient and dietary carbohydrate intake (g/kg body weight) were positively correlated at both 1 h (P < 0.01) and 2 h after baseline (P < 0.01). No relationship was observed between this gradient and mealtime insulin dose, or the glucose concentration at either time point. CONCLUSIONS: In patients with Type 1 diabetes, a clinically significant glucose gradient is present after the ingestion of a carbohydrate‐rich meal. As postprandial capillary and venous plasma glucose concentrations are not equivalent, defining the site of sample collection is important.