Reviews and reports

Cochrane Review – ‘human vs. animal insulin’

July 2002

It is the patient’s right to have an informed choice of treatment, with information about risks and benefits, including any adverse effects. People with diabetes have a right to an informed choice of insulin treatment and should be told of their choices. All too often they are not given information about the different species of insulin and are automatically prescribed GM synthetic insulin without being told that natural beef and pork insulins are available. Even when people are adversely affected by GM insulin, rarely are they advised to try natural animal insulin.

In order to have an informed choice of treatment, it is necessary to look at evidence from high quality systematic reviews. The following Cochrane Review comparing GM ‘human’ insulin and animal insulin provides just such high quality evidence.

"’Human’ insulin versus animal insulin in people with diabetes mellitus"

By Richter B, Neises G

This is an abstract of a regularly updated, systematic review prepared and maintained by the Cochrane Collaboration.

Background: Human insulin was introduced for the routine treatment of diabetes mellitus in the early 1980s without adequate comparison of efficacy to animal insulin preparations. First reports of altered hypoglycaemic awareness after transfer to human insulin made physicians and especially patients uncertain about potential adverse effects of human insulin.

Objectives: To assess the effects of different insulin species by evaluating their efficacy [in particular glycaemic control] and adverse effects [mainly hypoglycaemia].

Search Strategy: A highly sensitive search for randomised controlled trials combined with key terms for identifying studies on human versus animal insulin was performed using the Cochrane Library [Issue 2, 2002], Medline [1966 to May 2002]. We also searched reference lists and databases of ongoing trials. Date of last search: May 2002

Selection criteria: We included randomised controlled trials with diabetic patients of all ages that compared human to animal [for the most part purified pork] insulin. Trial duration had to be at least one month in order to achieve reliable results on the main outcome parameter glycated haemoglobin.

Data collection and analysis: trial selection as well as evaluation of study quality was performed by two independent reviewers. The quality of reporting of each trial was assessed according to a modification of the quality criteria as specified by Schulz and by Jadad.

Main results: Altogether 2156 participants took part in 45 randomised controlled studies that were discovered through extensive search efforts. Though many studies were of a randomised, double-blind design, most studies were of poor methodological quality. Purified porcine and semi-synthetic insulin were most often investigated. No significant differences in metabolic control or hypoglycaemic episodes between various insulin species could be elucidated. Insulin dose and insulin antibodies did not show relevant dissimilarities.

Reviewers’ conclusions: A comparison of the effects of human and animal insulin as well as of the adverse reaction profile did not show clinically relevant differences. Many patient-oriented outcomes like health-related quality of life or diabetes complications and mortality were never investigated in high quality randomised clinical trials. The story of the introduction of human insulin might be repeated by contemporary launching campaigns to introduce pharmaceutical and technological innovations that are not backed up by sufficient proof of their advantages and safety.

The full version of this Cochrane Review can be found at:

What does this review of ‘human’ and animal insulin mean for people with diabetes?
It provides us with information to make truly informed choices about the species of insulin we wish to use. Our choices are simple – animal insulins with a history of 70 years research and post marketing surveillance [being used in the real life situation for over 70 years] or ‘human’ insulin with an absence of meaningful research and an ongoing history of reported adverse reactions.

The review has dispelled many of the myths that are told to people with diabetes.

  • It can no longer be said that ‘human’ insulin is better than animal insulins, because there is no evidence for this.
  • It can no longer be said that ‘human’ insulin gives better control and better HbA1cs, there is no evidence for this.
  • It can no longer be said that ‘human’ insulin produces less antibodies, there is no evidence to support this.
  • The existence of other adverse effects, apart from hypoglycaemia, was not even investigated, so their existence can no longer be denied.

Important issues for people treated with insulin have never been investigated

Perhaps the greatest importance of this review is that it highlights the research that has NEVER been carried out. This absent research is essential for us to know that we are being treated with the insulin that produces the best effects on our health, our wellbeing and indeed our lives and even our life expectancy. These are very basic requirements for any drug but perhaps especially so for ‘human’ insulin – the first ever genetically produced drug to be used on human beings. Twenty years after its arrival on the market with indecent haste, ‘human’ insulin has never been subjected to essential, quality post marketing research to answer the questions that must now be asked by people who are prescribed it.