Glycaemic variability and ambient hyperglycaemia: How and when are they linked?

Postprandial and basal hyperglycaemia in type 2 diabetes: Contributions to overall glucose exposure and diabetic complications

Both postprandial and fasting (basal) hyperglycaemia contribute to overall hyperglycaemia (ambient hyperglycaemia) in type 2 diabetes (T2D). Postprandial glucose is the main contributor in fairly well controlled individuals, whereas basal hyperglycaemia becomes the preponderant contributor in poorly controlled patients. A more generally acceptable description of the contribution of postprandial glucose is to simply say that the absolute impact of postprandial glucose to HbA1c remains constant at approximately 1% across the entire HbA1c spectrum of non-insulin-treated patients with T2D. While epidemiological and pathophysiological studies seem to indicate that excessive postprandial glucose excursions play a role in or are predictors of cardiovascular diseases, there is still currently a lack of clinical evidence that correcting post-meal hyperglycaemia can improve clinical outcomes. However, even in the absence of consensus, there are many reasons for thinking that excessive postprandial glucose might be an independent risk factor for diabetic complications as it contributes to both overall glucose exposure and glycaemic variability, especially in those who have HbA1c levels < 7.5-8%. Given that excessive glucose fluctuations from peaks to nadirs activate oxidative stress, it seems reasonable to consider that a key player in the pathogenesis of diabetic complications, according to the latest IDF guidelines, is post-meal glucose, thereby warranting its assessment and treatment when found at abnormally elevated levels. Nevertheless, healthcare professionals should bear in mind that targeting both post-meal and basal plasma glucose, giving equal consideration to both of them, is probably the best strategy for achieving optimal glycaemic control and thus preventing or reducing the risk of diabetic complications.