Insulin can be used to treat people with Type 2 Diabetes at any time. It is the safest treatment to use during sepsis or organ dysfunction, so insulin is recommended for hospitalized patients. This section will help you to understand the different types of insulin, how to start and adjust insulin, and how to handle it. If your patients’ glucose levels are difficult to manage, this section helps you to understand why and how they may be improved.
The daily insulin profile: normal vs type 2 diabetes
Normally, insulin is secreted by the ß-cells in the pancreas at a low, steady rate in the background all day. This basal insulin controls the glucose produced by the liver (and, to a lesser extent by the kidneys) during periods of fasting and in between meals.
When carbohydrate foods are eaten, insulin responds briskly with two phases of secretion – an immediate first phase and a slower second phase.
The first phase is secreted immediately after sugar and high-glycaemic carbohydrate foods are eaten and absorbed very quickly. Without this first phase of insulin secretion, blood glucose levels spike sharply within minutes of eating carbohydrate foods. This insulin response is lost in people with pre-diabetes and type 2 diabetes.
The second phase of insulin secretion is later and slower, and matches with low-glycaemic index carbohydrates, which are absorbed more slowly. This response can be exaggerated in people with hyperinsulinemia (insulin resistance, pre-diabetes and early type 2 diabetes), when a large serve of sugar or high-glycaemic carbohydrate is eaten. This can lead to a delayed hypoglycaemic event 2 - 4 hours after the food was eaten and is called “reactive hypoglycemia”. How is this treated? Stop eating so much carbohydrate and change high-GI carbohydrates to low-GI carbohydrates.
Long acting insulin (Lantus, Toujeo or Protaphane)
These insulins work slowly to control the glucose levels before you eat food and while you are sleeping. It doesn’t have to be given with food. If you give this insulin at night time, it is better to give it at bedtime. It can be given on its own or it is combined with doses of rapid insulin at mealtimes.
Lantus and Toujeo
These are the same insulin, but they’re prepared at different concentrations – you get less fluid in the injection of Toujeo (more concentrated than Lantus). These are usually given once a day, although Lantus may need to be given twice a day to keep your glucose levels under control. If the dose is right, your glucose levels are in the target range before you eat.
This is a cloudy insulin that needs to be shaken vigorously before you inject it. If you don’t, it doesn’t get absorbed properly and your glucose levels can be quite unpredictable. It lasts for 16 hours, so it may need to be given twice a day.
Rapid-acting insulin (Apidra, Novorapid, Humalog)
These insulins work at meal times to control the glucose level after you eat. It is best to give the insulin dose 15 – 30 minutes before you eat, because it takes a while for the insulin to start working. The dose aims to match the food that you eat and lasts for about 3 hours. If you don’t eat the meal, you would skip the insulin dose. Your glucose levels are much easier to control if you avoid high-sugar foods – the insulin dose just can’t keep up.
Pre-mixed insulin (Novomix 30, Humalog Mix 25, Humalog Mix 50, Mixtard 30/70)
These insulins are a combination of rapid-acting insulin and a slower acting insulin. The rapid-acting insulin controls the glucose levels straight after you eat, and the lower acting insulin controls the glucose levels later in the day. It is a cloudy insulin that needs to be shaken vigorously before you inject it. If you don’t, it doesn’t get absorbed properly and your glucose levels can be quite unpredictable.
It is given once or twice a day – before breakfast and before dinner. It is best to give the insulin dose 15 – 30 minutes before you eat, because it takes a while for the insulin to start working. Your glucose levels are much easier to control if you avoid high-sugar foods – insulin just can’t keep up. This insulin needs to be injected with food, so you need to eat regularly. Otherwise, you may have hypos.
How to start insulin
When starting insulin, aim to choose a simple regimen that will safely introduce your patient to self-injection and improve glucose levels with the minimum risk of hypoglycaemia.
How to adjust basal insulin doses
Once you have started insulin, the doses will need to be increased regularly.
When to add rapid-insulin doses to basal insulin
If your patient is taking basal insulin (Lantus or Toujeo), but the glucose levels are high during the day, it is because the dietary carbohydrate is not being matched by the insulin. Adding rapid-acting insulin at meals will be more effective at controlling the glucose levels than increasing the dose of basal insulin.
When to add rapid-insulin doses to basal insulin
Step 1: Check your patient’s insulin response to food
Ask your patient to check glucose levels before and 1-2 hours after eating meals.
Also maintain a food diary for the same period, so that you can match the food to the glucose response. If your patient is eating lots of snacks, ask them to record these too as these will contribute to the pre-meal glucose levels.
There are two options for intensive glucose monitoring:
Option 1: Check glucose levels at each meal, every day for 1 – 2 weeks,
Option 2: Check glucose levels for one meal each day, but rotate between breakfast, lunch and dinner over the course of 2 – 4 weeks.
Step 2: Identify which meal is causing a spike in glucose level
Work with your patient to find which foods and meals consistently lead to post-meal glucose spikes. Rises of more than 3 mmol/L are significant, and glucose levels above 12 mmol/L require an action plan.
How to improve post-prandial glucose levels with food strategies:
When to consider pre-mixed insulin
Your patient may not want to start rapid insulin for meals and prefers a more convenient approach to controlling their glucose levels before and after meals.
You may consider a pre-mixed insulin if your patient:
You should not prescribe pre-mixed insulin if your patient is:
How to change insulin regimens
Improving your patient’s insulin injection technique
Getting the injection technique right makes a significant difference to how well glucose levels are controlled. Make sure your patient receives good education about injection technique, and this is reviewed regularly (See How to Inject Insulin). Insulin absorption is optimized by:
How to inject insulin: Instructions for patients
How to handle insulin
Side effects of insulin
Although insulin is an essential treatment for diabetes, it can cause side effects, particularly at higher doses. These can be minimized by keeping insulin doses as low as possible. This is best achieved by adhering to the lifestyle tips that improve insulin sensitivity. Side effects include: