06.04 Endo/Metabolic
06.04 Diabetes mellitus [PDF link]: T1DM, T2DM, Drugs used in DM & Insulin, DVLA rules for diabetes (driving), Complications of DM & sick day rules
More on T2DM
NICE guidelines NG28 covers management of T2DM, last updated Jun 2022
Seems like there will be new guidelines late in 2025 (with a bigger role of SGLT2I) – will keep an eye out for these.
There is also a NICE CKS page, with a lot more information on the drugs used in diabetes. Separate CKS page on insulin prescribing.
Variable rate intravenous insulin infusion (VRIII)
Scales for insulin infusion rate
| Glucose (mmol/L) | Standard rate |
|---|---|
| 4.1-8.0 | 1 |
| 8.1-12.0 | 2 |
| 12.1-16.0 | 4 |
| 16.1-20.0 | 5 |
| 20.1-24.0 | 6 |
| >24.1 | 8 |
Fluids for VRIII
Recommended: 0.45% NaCl with 5% glucose and 0.15% KCl (20 mmol/L), or 0.45% NaCl with 5% glucose with 0.3% KCl (40 mmol/L)
Alternatives: 5% glucose with 20 mmol/L or 40 mmol/L KCl, or 0.18% NaCl with 4% glucose with 0.15% KCl (20 mmol/L), or 0.18% NaCl with 4% glucose with 0.3% KCl (40 mmol/L).
Management of inpatient hyperglycaemia
Even if patient is not on insulin, they may still require Novorapid for deranged sugars (eg steroid-induced hyperglycaemia)
Use local trust policy in the first instance, but most policies will offer similar guidance
If CBG >12 mmol/L, check ketones as well
If BM >12 mmol/L + ketones <3, then ask them to check again in 2h
If ketones are raised, activate DKA protocol
If in doubt always do a VBG to monitor pH
If remains raised (>12mmol/L) and ketones normal, then administer Novorapid according to CBG reading
12.0-16.9 mmol/L – 2U
17.0-20.9 mmol/L – 3U
21.0-24.9 mmol/L – 4U
25.0-27.0 mmol/L – 5U
>27.0mmol/L – 6U
If ≥2 correction doses are required in 24h, consider starting basal insulin or increasing basal insulin dose by 10-20%
Can be done temporarily if needed, eg in people with steroid-induced hyperglycaemia
Refer to diabetic nurses for further input as well
NB: BM = Boehringer Mannheim, a pharmaceutical company that developed the glucose test strip – it’s a very outdated term but still commonly used (“monitor BMs”). Not to be mistaken for bowel movements. Also used is CBG – capillary blood glucose, which is more accurate.
References
George S, Dale J, Stanisstreet D, On Behalf of the Joint British Societies for Inpatient Care, And the Joint British Diabetes Societies Medical VRIII Writing Group. A guideline for the use of variable rate intravenous insulin infusion (VRIII) in medical inpatients. Br J Diabetes 2015;15:82. https://doi.org/10.15277/bjdvd.2015.014.
A similar document to this can be found here.
Prescribing insulin for insulin-naive patients
The above VRIII guideline has some useful information about how to calculate an appropriate starting insulin dose
Weight-based calculations – generally the total daily dose (TDD) is 0.5 x body weight (kg)
Apart from frail elderly pts, pts with CKD 4/5, or new T1DM, in which the formula is 0.3 x body weight
This NICE CKS page goes through different insulin regimes. In practice, the prescribers are usually endocrinologists or diabetes nurse specialists (DSNs).
