CAT: Therapy: MI, hyperglycaemia: Insulin therapy

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MI - MIs WITH HYPERGLYCAEMIA BENEFIT FROM INTENSIVE INSULIN THERAPY.

Clinical Bottom Line:
Treating 9 hyperglycaemic MI patients with intensive insulin => 3 months will prevent one additional death over the next 3.4 years.

Appraised by: Sackett; 24 October 1997

Clinical Scenario: A 48 year-old man in prior robust health is admitted with 4 hours of central chest pain and ST elevation in 2 adjacent leads. Despite thrombolysis he has an uncomplicated myocardial infarction. His admission blood sugar is 13 mmol/l.

Three-part Question: In an otherwise low-risk MI patient with hyperglycaemia, would an intensive insulin regimen reduce the rtisk of recurrent MI or death?

Search Terms: None; recalled from spending 40 minutes every 8 weeks reading Evidence-Based Medicine.

The Study:
Non-blinded concealed randomised controlled trial with intention-to-treat. Swedish patients admitted with MI in the prior 24 hours with blood glucose >11 mmol/l with or without prior known diabetes. 50% thrombolysed; by discharge 80% given aspirin, 70% given beta-blockers, and 31% given ACE-inhibitors.
Control group (N = 314; 314 analysed): Routine MI care (including aspirin and beta-blockers) but no (extra) insulin unless "clinically indicated" (43%, 45% and 49% on insulin at discharge, 3 months, and 1 year).
Experimental group (N = 306; 306 analysed): Routine MI care plus glucose+insulin infusion for =>24 hours and qid insulin for =>3 months (87%, 80% and 72% on insulin at discharge, 3 months, and 1 year).

The Evidence:
Outcome Time to Outcome CER EER RRR ARR NNT

death (all patients) 3.4 years 0.439 0.333 24% 0.106 9

95% Confidence Intervals: 7% to 41% 0.030 to 0.182 5 to 34

Outcome	Time to Outcome	CER	EER	RRR	ARR	NNT
death (all patients)	3.4 years	0.439	0.333	24%	0.106	9
95% Confidence Intervals:	7% to 41%	0.030 to 0.182	5 to 34

Comments:

Benefit greatest in low risk patients (<70 y/o, no prior MI, no CHF, no digitalis Rx) not previously on insulin (RRR 46%; ARR 0.15; NNT 7).
PTCA and CABG done in 5% and 11% of controls and in 4% and 11% of intensive insulin patients.
Glucose 11.7 and 9.6 at 24 hours; 9 and 8.2 at discharge.
97% of deaths were cardiovascular, and most of the mortality benefit was seen after discharge.

Expiry date: October 1998

Reference:

Malmberg K for the DIGAMI Study Group: Prospective randomised study of intensive insulin treatment on long term survival after acute myocardial infarction in patients with diabetes mellitus. BMJ 1997;314:1512-5.

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