Understanding glucose curves: monophasic, biphasic and incessant increase responses

There are three major glucose curves: monophasic, biphasic, and incessant increase. Discover the underlying causes behind these curves, their implications for health and tips for improving your glucose responses.

Key takeaways

• In oral glucose tolerance test (OGTT) studies, a monophasic curve has been linked with lower insulin sensitivity and a higher risk of type 2 diabetes. It is an association, not a diagnosis.
• In OGTT studies, people with a biphasic curve tended to have better insulin sensitivity and a lower risk of type 2 diabetes.
• In OGTT studies, a curve that keeps rising was linked with lower beta cell function and the highest risk of type 2 diabetes.
• Understanding the causes of different glucose curves can help identify factors that influence glucose levels and inform effective management techniques.

How your body handles a large dose of sugar says something about your metabolic health. Monophasic, biphasic and incessant increase glucose curves come from oral glucose tolerance test research, where they reflected different levels of metabolic fitness.

What are the three types of glucose spikes?

• Monophasic glucose response: characterised by a single glucose peak followed by a consistent decline. In OGTT studies this curve has been linked with a weaker first phase of insulin release.
• Biphasic glucose response: features an initial peak 30-60 minutes post-meal, a drop in glucose levels, and then a secondary increase between 90-120 minutes. In OGTT studies this curve is linked with a stronger first phase of insulin release and better insulin sensitivity.
• Incessant increase: a continuous gradual rise in blood sugar in the 120 minutes post-meal without a fall of at least 0.25 mmol/L (4.5 mg/dL).

These shapes were defined from a 75 g glucose drink taken in a lab, not from everyday meals on a CGM. One meal curve on a CGM cannot classify you; if you are worried, ask your GP about an OGTT or HbA1c.

Implications of monophasic, biphasic and incessant increase glucose responses

In OGTT studies, people with a biphasic response tended to have:

• Enhanced health outcomes
• Decreased glucose levels
• Lower fasting insulin levels
• Reduced BMI
• Increased insulin sensitivity
• Fewer instances of impaired glucose tolerance and metabolic syndrome

Research demonstrates that individuals with monophasic responses after consuming large amounts of carbohydrates may have a lower metabolic health profile. This may include:

• Reduced insulin sensitivity
• Decreased pancreatic beta cell function
• Elevated glucose levels
• Increased fasting insulin levels
• Higher insulin levels two hours post-glucose consumption
• A higher prevalence of metabolic dysfunction and impaired glucose metabolism

Those with an incessant increase response tend to display an even lower metabolic health profile:

• Even poorer pancreatic beta cell function
• Insulin resistance
• Decreased glucose tolerance
• May indicate a faster decline of beta cell function
• Increased risk of type 2 diabetes

The underlying causes of monophasic, biphasic and incessant increase glucose spikes

The disparity between these curves may be linked to the two insulin release phases following glucose consumption:

• First phase: rapid onset after glucose consumption, with a short duration
• Second phase: begins later and is more prolonged

Individuals with a monophasic response experience a reduced and compromised first phase of insulin release. Those with an incessant increase may have an even lower insulin response, due to poor beta cell function.

In contrast, those with a biphasic response enjoy superior insulin release during the first phase and increased insulin sensitivity. Additional factors, such as the rate of stomach emptying and hormonal influences, may also affect the glucose curve.

Tips for improving your glucose responses

Although a biphasic OGTT curve is linked with better health outcomes, repeated high glucose peaks after meals can still be a risk factor for poor health.

The optimal glucose curve remains relatively flat throughout the day, with minimal fluctuations, staying within the desired range. Ideally, the curve displays minimal glucose variability.

Using a continuous glucose monitor (CGM) can shed light on your glycaemic control patterns and aid in enhancing metabolic health over time. To maintain optimal glucose management, consider implementing the following strategies:

• Regularly monitor blood glucose levels with a CGM
• Choose low-GI foods where possible and pair your high carb foods with protein, fats and fibre
• Distribute carbohydrates evenly throughout the day
• Engage in regular exercise, and exercise you enjoy
• Seek personalised advice from a healthcare professional

Recognising the distinctions between monophasic, incessant increase and biphasic glucose responses can help you understand your metabolic health better. By pinpointing factors that influence glucose levels and adopting effective management techniques, you can work towards achieving better health outcomes and improved metabolic fitness. As always, consult a healthcare professional if you have concerns about your glucose levels or require personalised guidance.

Knowing your glucose range is useful, but real progress comes from understanding how different foods shape your glucose curve. Vively’s CGM program gives you real-time data, helping you move beyond averages to truly personalised insights.

In this one member's example, regular bread rose to 8.6 mmol/L while low-GI bread stayed at 4.4 mmol/L. Responses vary from person to person: see the member medians for white bread and sourdough. Tracking your own responses helps you see which foods suit you.

Vively is an Australian health membership. Its CGM program shows your glucose readings in the Vively app against a 4 to 6 mmol/L range, alongside your other health data, education and support.

References

1. Li, Y., Xu, W., Liao, Z., Yao, B., Chen, L., Wu, J., ... & Zhao, X. (2018). A biphasic glucose curve during an oral glucose tolerance test and the risk of incident cardiovascular diseases in Chinese adults. Journal of Diabetes Research, 2018. https://doi.org/10.1155/2018/9823627
2. Nathan, D. M., Kuenen, J., Borg, R., Zheng, H., Schoenfeld, D., & Heine, R. J. (2003). Assessing the shape of the glucose curve during an oral glucose tolerance test. Diabetes Care, 26(4), 1026-1032. https://doi.org/10.2337/diacare.26.4.1026