Type 2 diabetes on basal insulin

About 1.5 million adults in the US live with type 2 diabetes, take basal insulin without mealtime insulin, and use a CGM.¹ Most writing about insulin and technology assumes multiple daily injections or a pump. This page is for people on basal insulin alone.

Basal insulin is background insulin. It covers the body's steady need for insulin between meals and overnight. On injections, it is usually a long-acting insulin, taken once or sometimes twice a day.

Because it works around the clock, much of what it does happens while you are asleep.

Many people on basal insulin are asked to keep an eye on their fasting glucose, the reading when they wake up before eating. That number is key because it reflects how the night went.

One reading tells you where you ended up. It doesn’t tell you how you got there. A normal morning can follow a night that went low and then came back up. A high morning can come from a rise in the early hours rather than from the evening before.

Why blood sugar can be high in the morning

A CGM records glucose every few minutes, so the overnight hours become visible instead of inferred from one number. Two weeks of data is usually enough to show a pattern: whether you drift up toward morning, whether you dip in the early hours, and how often either happens.

In a 2026 survey of 583 adults with diabetes, including 177 with type 2 on basal insulin and a CGM, people ranked what they want from their nights.² Avoiding lows came first, then waking up at a glucose level they were happy with. Avoiding highs during the night ranked lower, and lower still among people with type 2.³

Any insulin can cause a low, including at night. If you wake with symptoms, or your CGM shows dips overnight, tell your care team.

• What does my CGM show between midnight and waking?
• Are my morning readings telling us about my basal dose, or about something else?
• Am I going low at night without knowing?

How to talk to your doctor about your nights

This page explains how basal insulin and overnight glucose relate. It is not guidance about your own dose, which belongs with your clinician.