• For symptoms and signs, investigations and guideline to use, see Hyperglycaemia: triage guideline

Appropriate patients

• Patients with blood glucose persistently >12 mmol/L with:
• mild/no dehydration
• able to eat and drink
• no metabolic acidosis nor severe dehydration

Investigations

• Blood glucose (capillary)
• if persistently high, check venous blood glucose

• Never give single doses of insulin (e.g. Actrapid)
• Refer to diabetes team
• Withhold metformin, gliptins and GLP analogues (exenatide and liraglutide) and SGLT2 inhibitor if:
• renal impairment as defined by creatinine >130 µmol/L and eGFR <45 mL/min
• decompensated cardiac failure
• liver failure or lactic acidosis

Patient on regular insulin

• Increase usual total daily insulin dose by 10-20%

Patient taking oral agents only

• Add low-dose long-acting insulin or insulin analogue 
• such as 10–12 units of isophane, glargine, detemir, semglee, degludec or toujeo
• if high risk of hypoglycaemia (e.g. elderly patient with variable oral intake), prefer glargine semglee, degludec or toujeo to isophane or determir
• If morning fasting glucose is >12 mmol/L, add at bedtime or
• If pre-evening meal glucose is >12 mmol/L, add at breakfast time or
• If both morning fasting and pre-evening meal glucose are >12 mmol/L, add at bedtime and breakfast time
• If taking pioglitazone, be alert for appearance of dyspnoea or peripheral oedema
• introduction of insulin can precipitate heart failure

Patient on no drug treatment for diabetes

Renal impairment

• If liver dysfunction as well, follow next section on Liver dysfunction
• Otherwise, if eGFR <45 mL/min (metformin contraindicated), use sulfonylureas

Liver dysfunction

• if more than a 4-fold rise in liver enzymes:
• no oral hypoglycaemic agents
• find cause of raised liver enzymes
• use insulin, see Patient taking oral agents only above

Normal renal/liver function

• Start on metformin as first line
• irrespective of BMI
• starting dose 500 mg once daily; routinely in order to reduce frequency of administration and improve compliance, advice is given to increase dose to 500 mg twice daily after 1 week - gradually maximised to 1 g twice daily

• Capillary blood glucose 4-hrly

• Encourage early mobilisation
• Check with diabetes team about out-patient review
• If patient new to insulin, do not forget to prescribe needles for insulin pens, lancets and sharps guard