Tayside Diabetes MCN Handbook
Management of Diabetes in Acute Coronary Syndrome

Diabetes Mellitus

Patients with type I and type 2 diabetes require special management when they present with acute coronary syndromes. Some patients, who are not previously known to have diabetes, can present with hyperglycaemia, so called “stress hyperglycaemia”. Patients not known to be diabetic but presenting with a laboratory blood glucose (BG) > 11mmol/L should also be treated in this way. IV insulin infusion should be commenced for acute management in first 24-48 hours. Patients with type 1 diabetes should continue their usual basal (long acting insulin) e.g. Lantus/ Levemir daily to reduce the risk of diabetic ketoacidosis if IV insulin is interrupted.

Initial Management in first 24-48 hours

Insulin and glycaemic control

Add 50 units of soluble insulin (e.g. Actrapid) to 50 ml 0.9% NaCL (1 unit insulin / ml, thus 1 unit / hour = 1ml / hour). Infuse using a syringe driver. Check a fingerpick BG level hourly during the day and 2 hourly once stable and at night. The aim to of management is to optimise glycaemic control (5-9 mmol/L) without hypoglycaemia. Consider 10% glucose infusion if BG remains < 6 mmol/L. Prescribe insulin infusion as:

BLOOD GLUCOSERATE OF INSULIN INFUSIONINTRAVENOUS FLUIDS
500 ml/ 12 hour
> 16.0 mmol/L 10 unit / hour 0.9% NaCl
12.1 – 16.0 mmol/L 6 unit / hour 0.9% NaCl
10.1 – 12.0 mmol/L 4 unit / hour 0.9% NaCl
8.1 – 10.0 mmol/L 3 unit / hour 0.9% NaCl
6.1 – 8.0 mmol/L 2 unit / hour 0.9% NaCl
4.1 – 6.0 mmol/L 1 unit / hour 10% Glucose
< 4.0 mmol/ 0.5 unit / hour 10% Glucose

IV insulin pumps should never be switched off as the half life of IV insulin is < 3 minutes.

IV fluids

IV fluid should run through the same IV access as the insulin infusion. Infuse at least 500ml / 12 hours. The rate of infusion can be varied depending on the patient’s fluid status. In cases of CCF or pulmonary oedema requiring fluid restriction the rate of IV fluid can be decreased to 500 ml / 24 hours.

Potassium

Serum potassium should be measured at entry to CCU and then at 6, 12 and 24 hours. Potassium should be added to the IV fluid depending on the patient’s serum K+. No potassium should be added if serum K+ > 4.9 mmol/L or if there is renal impairment i.e. eGFR < 30ml/min.

Subsequent management after 24-48 hours

Continue IV insulin for at least 24 hours or until clinically stable and tolerating fluids and diet. Use recent HbA1c to assess success of previous diabetes therapy i.e. last 3 and 6 month estimations (target HbA1c 6.5 - 7.5%).

  

Conversion to Insulin

Type I diabetes/ type 2 diabetes normally prescribed insulin:

  1. Restart usual subcutaneous (SC) insulin preparation and dose at suitable mealtime
  2. Stop IV insulin one hour after subcutaneous insulin administration.
  3. Titrate dose to optimise glycaemic control

Type 2 diabetes with suboptimal HbA1c where oral medication cannot be increased or medication contraindicated. Consider conversion to insulin therapy.

  1. Calculate insulin dose by determining number of units of IV insulin required in the last 24 hours.
  2. E.g. if total 24-hour insulin requirements = 30 units, then prescribe as 20 units insulin before breakfast, 10 units insulin before tea. (Mixtard 30 or Novomix 30 are suitable insulin preparations).
  3. Start usual subcutaneous (SC) insulin at suitable mealtime.
  4. Stop IV insulin one hour after subcutaneous insulin administration.
  5. Titrate dose to optimise glycaemic control.

For further information, see Handbook sections Treatment with Insulin and Adjustment of Insulin

 

Conversion to oral medication

Type 2 normally prescribed oral medication

Restart usually oral medication* at suitable mealtime then stop IV insulin.

 

Type 2 normally treated with healthy eating with suboptimal HbA1c

  1. Commence oral medication
  2. Metformin is the usual 1st choice agent but for further information see Handbook sectionTreatment with Oral Hypoglycaemic Agents

 

 *Metformin

should be avoided if there are any of the following: Grade III/IV heart failure, if eGFR is < 30ml/min (creatinine >150ummol/L) and/or liver failure. If eGFR is 30-50ml/min reduce metformin dose by 50% or to maximum dose of 500mg BD.

 

*Glitazones (rosiglitazone, pioglitazone) should both be avoided if clinical heart failure or LV dysfunction is present. Rosiglitazone is contraindicated in patients with acute coronary syndrome and it should be avoided in patients with underlying IHD or PVD. For further information see www.emea.europa.eu/pdfs/human/press/pr/4223208en.pdf

 

Not previously known to have diabetes

Distinguish between diabetes and stress hyperglycaemia. Patients with a laboratory glucose greater than 11 mol/L on admission probably have diabetes. If the plasma glucose is between 8.9 and 11 mmol/L then they may have diabetes or impaired glucose tolerance and if the admission plasma glucose in less than 8.9 mmol/L then they are unlikely to have diabetes.

A fasting blood glucose should be performed at least 48 h after admission in cases of doubt. If the fasting plasma venous glucose is < 6.0 mmol/L then no further action is required but those with a fasting plasma venous glucose > 7.0 mmol/L have diabetes and will require dietary advice and/ or further treatment prior to discharge.

See Handbook section Diagnosis of Diabetes for further information

Lifestyle management and follow up

  1. Titrate insulin/ medication and optimise glycaemic control
  2. Provide diabetes information/ education
  3. Refer to Diabetes Specialist Nurse for specific advice
  4. Refer to dietician if newly diagnosed, treatment changed to insulin or for improvement of diabetes management.
  5. Refer to diabetes clinic with relevant background medical history (copy letter to Angus or PRI casenotes if the patient does not attend the diabetes clinic in Ninewells Hospital).
  6. Diabetes management information and patient leaflets available www.diabetes-healthnet.ac.uk
  7. Contact details for diabetes team:
    Ninewells Hospital - SpR Diabetes bleep 5416, Diabetes Specialist Nurse, ext 36009, bleep 4872
  8. Perth Royal Infirmary – Specialist Nurse bleep 5288/5164

 

Management of Diabetes following Myocardial Infarction

 

Back to the top Back to the top of this page