From the Guidelines
The body typically increases insulin production at night as part of its natural circadian rhythm, particularly during the early morning hours in what's known as the dawn phenomenon, and this variation is crucial for people with diabetes to understand and manage their blood glucose levels effectively. This occurs because the body releases growth hormone, cortisol, and other hormones during the early morning hours (around 3-8 AM), which can cause insulin resistance and prompt the pancreas to produce more insulin to maintain blood glucose levels 1. Additionally, during the first part of sleep, the body often experiences decreased insulin sensitivity, requiring more insulin to manage blood glucose.
The principal action of basal insulin is to restrain hepatic glucose production and limit hyperglycemia overnight and between meals, and attainment of fasting glucose goals can be achieved with human NPH insulin or a long-acting insulin analog 1. In clinical trials, long-acting basal analogs (U-100 glargine or detemir) have been demonstrated to reduce the risk of level 2 hypoglycemia and nocturnal hypoglycemia compared with NPH insulin 1. Longer-acting basal analogs (U-300 glargine or degludec) convey a lower nocturnal hypoglycemia risk compared with U-100 glargine 1.
For those with diabetes, medication timing might need adjustment to account for these natural fluctuations - some may benefit from taking longer-acting insulin before bed or using an insulin pump programmed with different basal rates overnight. Clinicians should be aware of the potential for overbasalization with insulin therapy, and clinical signals that may prompt evaluation of overbasalization include basal dose greater than 0.5 units/kg, high bedtime-to-morning or preprandial-to-postprandial glucose differential, hypoglycemia (aware or unaware), and high variability 1. It is essential to monitor for signs of overbasalization during insulin therapy and reevaluate the treatment plan promptly to further tailor therapy to the individual’s needs.
From the Research
Insulin Increase at Night
- The body's natural insulin production and regulation can be influenced by various factors, including diet, physical activity, and medication 2, 3, 4, 5, 6.
- Research has shown that certain medications, such as pioglitazone and metformin, can affect insulin sensitivity and glucose metabolism in patients with type 2 diabetes 3, 4, 6.
- A study published in 2025 found that a continuous glucose monitoring-based insulin titration protocol can be effective in managing insulin levels in inpatients with type 2 diabetes in non-intensive care unit settings 5.
- Another study published in 2006 developed a mechanism-based disease progression model to compare the long-term effects of pioglitazone, metformin, and gliclazide on disease processes underlying type 2 diabetes mellitus 6.
- However, there is no direct evidence to suggest that the body increases insulin production at night, and more research is needed to fully understand the relationship between insulin regulation and circadian rhythms.
Factors Affecting Insulin Regulation
- Diet and physical activity can impact insulin sensitivity and glucose metabolism 3, 4.
- Certain medications, such as pioglitazone and metformin, can affect insulin sensitivity and glucose metabolism in patients with type 2 diabetes 3, 4, 6.
- Continuous glucose monitoring-based insulin titration protocols can be effective in managing insulin levels in inpatients with type 2 diabetes in non-intensive care unit settings 5.
Medications and Insulin Regulation
- Pioglitazone and metformin are commonly used medications to manage type 2 diabetes, and they can affect insulin sensitivity and glucose metabolism 3, 4, 6.
- A study published in 2005 found that pioglitazone improves postload glycemia and composite insulin sensitivity index more than metformin or gliclazide when used as monotherapy or in combination therapy in patients with type 2 diabetes 3.
- Another study published in 2010 found that pioglitazone and metformin had comparable effects on estimates of carbohydrate metabolism and insulin sensitivity in high-fat fed rats, but different effects in diabetic rats 4.