Why Depression Is Not “Just Like” Diabetes

The idea that mental disorders are an illness or disease “just like” diabetes is a commonplace. The website of the American Psychiatric Association (APA) indicates that mental illness “is a medical condition, just like heart disease or diabetes.” In fact, the equivalence of mental and medical illnesses, like diabetes, is so taken for granted in psychiatry that it has become “almost axiomatic.”¹

The diabetes analogy serves a rhetorical purpose. In public forums, it is often employed to counter stigmatizing attitudes toward mental illness. The quote above from the APA follows its reassurance that “mental illness is nothing to be ashamed of!” Mental suffering is real and painful and the hope of those using the analogy is that by stressing the biogenetic aspects of psychopathology, the public can be persuaded to not hold sufferers responsible for their condition.

The analogy is also used to promote parity in insurance coverage and foster patient help-seeking and treatment. In clinical settings, doctors compare psychological distress to conditions like diabetes as a way to relieve self-blame and convince reluctant patients to start or stay on medication.

The point of the analogy is to establish that mental disorders are, just like diabetes, physical illnesses. As diabetes is a dysfunction in the pancreas, so mental disorder is a dysfunction in the brain. As diabetes reflects flaws in glucose metabolism, so the mental states involved in mental disorders—thoughts, emotions, and their regulation—reflect some underlying flaw in biology, whether a neurotransmitter imbalance, brain lesion, or neural circuitry problem. As diabetes typically requires medication treatment with insulin, so mental suffering requires psychiatric medication to correct the underlying dysfunctional mechanism.

If we compare mental disorders and diabetes, we will find some things in common. Both can be responsive to medications, for instance. One cannot just snap out of either and neither should be the occasion for shame. Especially in the case of psychosis and bipolar disorders, both involve hereditary vulnerabilities, and diabetes (type 2) also has a behavioral component (e.g., poor diet, lack of exercise).

In most respects, however, the analogy is deeply misleading. The “just like” equivalence implies that we understand the physiology of mental disorders and can answer complex questions about the relation of thoughts, feelings, and actions to brain states. We cannot. Current psychiatric research explains psychopathology as arising from “multiple biological, behavioral, psychosocial, and cultural factors, all interacting in complex ways and filtered through an individual’s lifetime of experience.”² Every case is different and our neuro-scientific knowledge does not allow us to distinguish which of our mental states or behaviors—even those that might be strange or undesirable—have meaning and may be warranted and which are “diabetes-like,” that is, without reasons or content of any kind.

But the real danger of the analogy is on the more practical level, where the equivalence implies that dealing with a condition like depression, say, is or should be “just like” dealing with diabetes or other chronic illness. Drawing on my experience interviewing people suffering from psychological distress and treated for depression and anxiety disorders, I want to briefly consider three aspects of this implication. Interviewee predicaments were not equivalent to having diabetes and imagining such can only lead to confusion and misguided practices.

A first practical implication of the analogy is that the nature of the suffering is much the same. Medical conditions, like diabetes, are explained on the basis of physiologic mechanisms. While they can, of course, cause pain, distress, and inconvenience, questions of self-understanding, personal worth, social aspirations, or cultural values are out of place. It is a category error to raise them.

The suffering involved in depression, anxiety, and so forth is quite different. The people I interviewed reported a lack of focus, feelings of inadequacy, inability to get out of bed, broken dreams, and doubts about their life choices. They believed they were inadequately optimizing their potential, couldn’t shake off losses quickly, or efficiently control their emotions. They worried what others thought of them, felt they had an insufficiently outgoing personality, and so on. Even those interviewees who referenced genetics and neurochemistry thought that more than some malfunctioning of the brain was at stake. Their suffering was bound up with their very status as persons and their relations with others and the world around them. To rule out this context, a priori, as needless or misplaced was to miss what really mattered.

A second practical implication is that personal meanings are unimportant. Regular medical diagnoses, like diabetes, where clear and common understandings of malfunctioning exist, do not depend on personal definitions or the patient’s conceptual capacity to understand them. This is so because diabetes itself is not a psychological state, or an attitude, or a way of seeing the world. It is diagnosed from biomarkers of glucose metabolism.

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For depression, anxiety, and other mental suffering, by contrast, there are no blood tests. Nor could there be. What makes the experience feel the way it does, or what causes it to induce shame, worry, or disappointment is not independent of the person who has the experience. It reflects their situation and first-person evaluative stance, and the people I interviewed often complained of brief, cursory physician appointments that centered on “symptoms” ascertained by checking boxes on a questionnaire. What they wanted, in the first instance, was to be listened to.

A third practical implication is that medication will normally be the primary (and long-term) treatment and that taking a psychiatric medication is like taking insulin. While diet and exercise might be enough in some cases of diabetes, insulin is the primary and life-saving therapeutic tool. It works directly to improve glucose metabolism and in no way depends on the diabetic’s subjective judgment.

The treatment of mental suffering is more complex and multifaceted. In my interviews, people coped with their struggles in a variety of different ways—with psychotherapy, with medication, with a combination, with neither. For those taking medication, whether the drug was “working” or not—an on-again, off-again proposition—was based on their personal assessment. This judgment was seldom expressed in terms of any physiological change. It was a question of how they felt about themselves and their situation. Many wanted to eventually go off their medication but didn't know how to make that decision. The default at their med check appointments was to stay the course.

The diabetes analogy is offered by medicine as a benign truism and reassuring explanation. Yet it is not benign. If my interviews are any indication, it misinforms a lot of clinical practice, fosters the misunderstanding of mental suffering, and, as I have noted elsewhere, actually contributes to rather than reduces stigma. Depression is not “just like” diabetes and it’s time to stop saying that it is.