Hair Loss in a Female Patient with Diabetes: What’s the Cause?

Diagnostic Workup

Hair grows in cycles, each involving metabolic events that ultimately generate the hair shaft. Consequently, anything that interferes in any of those cycles can result in hair loss. Common causes of these cycle interruptions are medications, illness or stress, infection or environmental chemicals. Other frequent reasons for hair loss in women are pregnancy or recent delivery, thyroid disorders and autoimmune conditions.

Hair loss is a disturbing phenomenon usually noticed in a woman’s post-menopausal years, but is not specific to that age range. Women typically present with complaints similar to those expressed by Mrs. S, with increased hair in the drain, in the brush or on the pillow.

Having largely ruled out environmental and reproductive factors in Mrs. S’s case, assessment was then turned to laboratory investigation.

Mrs. S’s serum albumin was normal at 4.5g/dL and her thyroid stimulating hormone (TSH) was also normal at 2.7µl/mL. Although her complete blood count and red cell indices were within normal limits, it was noted that the hemoglobin had decreased slightly since last testing, and the red cell index of mean corpuscular volume (MCV) had risen from 87.2fL to a high normal value of 97.2fL.

Since macrocytosis is often one of the earliest laboratory abnormalities seen in patients with folate or vitamin B12 deficiency, a serum B12 level was obtained. Mrs. S’s vitamin B12 level was 198pg/mL (normal range 213-816pg/mL).


Since first introduced in the United States, metformin (Glucophage, Fortamet, Glumetza and Riomet) has rapidly become a mainstay in diabetes management. However, as the years progressed, evidence has accumulated to show that long-term metformin use is associated with B12 deficiency.

It is estimated that among persons with diabetes who have been taking metformin for ≥10 years, 30% will have low B12 levels. The mechanism of action of this side effect is thought to involve the disruption of intrinsic factor in the gastric mucosa. This begins the chain reaction of increased red cell fragility and decreased iron absorption, with eventual impact on multiple body systems.

B12 deficiency generally affects any area of rapidly dividing cell growth. Since most Americans’ B12 hepatic stores are sufficient for about four years, such deficiencies are usually subtle and have a slow onset.

Consequently, in Mrs. S’s case, her hair complaint was an early warning of further problems that were successfully avoided with B12 supplementation. She was started on 1,000mcg of cyanocobalamin every other week for two doses, and then monthly.

In the last few years oral B12 supplementation has been successful, but with much slower accumulation than parenteral forms. Mrs. S’s hair loss gradually decreased over the next two to three months and has remained normal since that time.

Sherril Sego, FNP-C, DNP, is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women’s health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas.


  1. Aslinia F et al. “Megaloblastic anemia and other causes of macrocytosis.” Clin Med Res. 2006;4(3):236–241.
  2. Breitkopf T et al. “The basic science of hair biology: What are the causal mechanisms for the disordered hair follicle?” Dermatol Clinics. 2013;31(1):1-19.
  3. Gupta M. “Revisiting Metformin: Annual vitamin B12 supplementation may become mandatory with long-term metformin use.” J Young Pharm. 2010;2(4):428-429.

This article originally appeared on Clinical Advisor