Introduction
Glucose levels above 11 mmol/L increase the risk of immediate complications, including polyuria, gastroparesis and elevated risk of infection.
High blood glucose levels bind to circulating and endothelial proteins. This is useful as a diagnostic tool, where HbA1c reflects the blood glucose levels over the 3-month lifespan of red blood cells.
However, high blood glucose levels are very damaging to these proteins over a prolonged period, and lead to:
The risk of these complications increases exponentially above an HbA1c of 6.5%.
Conversely, reducing the HbA1c by 1% reduces the risk of microvascular complications by more than one-third. Keeping the HbA1c below 7% reduces the risk of long term vascular complications, but this is improved further by controlling blood pressure and cholesterol.
Consequences of hyperglycemia
While hyperglycemia increases the long-term risk of vascular complications, the immediate symptoms affect your patients’ quality of life right now.
The short-term effects of high glucose levels (above 11 mmol/L) include:
The high glucose levels themselves impair insulin secretion and increase insulin resistance. Therefore, hyperglycaemia worsens and prolongs the hyperglycaemia.
All of these effects of hyperglycemia are improved by reducing glucose levels to 4 – 10 mmol/L.
Troubleshooting for causes of hyperglycemia
Although diabetes medications are first thing we think of as the cause of high glucose levels or a rising HbA1c, it’s important to consider all possible causes of high glucose levels before medications are changed. Working on these non-medication causes of hyperglycemia often leads to greater improvements in HbA1c than changing the medications.
1. Check that the glucose level is trusted
2. Diet is high in sugar and carbohydrate
3. Poor sleep quality
4. Stress or sickness
5. Steroid therapy
6. Infection
7. Constipation
8. Not taking tablets or insulin
9. Poor insulin injection technique
10. Tablets are no longer effective
11. Insulin doses are not right
Which medication next?
When your patients’ HbA1c continues to rise, you need to choose the next best medication to add to the regimen. Your choice of agent will depend on the current regimen, the renal function and the balance between benefit and side effect profile of the medication.
Use this to guide to choose the right medication for your patient. For each option provided, a star rating is offered to balance the benefit of each medication to its side effect profile. Some combinations are limited by PBS subsidy (Pharmaceutical Benefits Scheme), not clinical benefit.
Current medications: Metformin only
Current medications: Metformin & Sulphonylurea
Current medications: Metformin & DPP4-inhibitor
Current medications: Metformin & Sulphonylurea & DPP4-I
Current medications: Metformin & SGLT-2i
Current medications: Metformin & Sulphonylurea & SGLT-2i
Current medications: Metformin & GLP-1 agonist
Current medications: Sulphonylurea & GLP-1 agonist
When to start insulin
While insulin can be started at any time as treatment for people with type 2 diabetes, it is often reserved for situations when other treatments are ineffective or could cause harm. Insulin may used temporarily, or as an ongoing treatment plan.
Temporary treatment with insulin is the recommended for hyperglycemia in these situations:
Ongoing treatment with insulin is recommended in the following situations:
Which medications can be added to insulin
Rather than increasing insulin doses, medications can be added to insulin to improve glucose control. Use this guide to rationalise the medication plan.
For each option provided, a star rating is offered to balance the benefit of each medication to its side effect profile. Some combinations are limited by PBS subsidy (Pharmaceutical Benefits Scheme), not clinical benefit.
Current medications: Metformin only
Current medications: Metformin & Sulphonylurea
Current medications: Metformin & DPP4-inhibitor
Current medications: Metformin & Sulphonylurea & DPP4-Inhibitor
Current medications: Metformin & SGLT-2i
Current medications: Metformin & Sulphonylurea & SGLT-2 inhibitor
Current medications: Metformin & GLP-1 agonist
Current medications: Sulphonylurea & GLP-1 agonist
Steroids and hyperglycemia
Steroid medications cause insulin resistance and a typical pattern of hyperglycaemia where glucose levels may be expected to peak after lunch and dinner and fall to lower glucose levels overnight. While the pattern of hyperglycaemia is the same for the different types of glucocorticoids, the degree of hyperglycaemia is related to the steroid dose. If your patient is on insulin, the dose will need to be titrated according to the dose of steroid.
Managing steroid-induced hyperglycemia will be easier if your patient:
Stress and sickness
Significant stress and illness raise glucose levels due to insulin resistance caused by elevated cortisol levels as well as sleep deprivation and poor food choices. Hyperglycemia can delay the recovery from illness and emotional stress, so it’s important to have strategies to manage the diabetes during these periods.
These strategies include:
If your patient is on insulin, the doses may need to be increased if the hyperglycaemia is significant, and the period of illness is prolonged. The dose adjustment will depend on the pattern of hyperglycaemia and the current insulin regimen.
Plan to increase the dose of basal insulin by 10 – 20% every week. If your patient takes rapid-acting insulin, consider adding correction doses to their usual doses of rapid-acting insulin. Estimate that 1 unit will lower glucose levels by 1 mmol/L.