Cataract is a rare manifestation of type 1 diabetes mellitus with prevalence being around 0.7-3.4 % [1] [2]. It usually develops around 5 years after the diagnosis of diabetes mellitus. The cataract associated with type 1 diabetes mellitus is called as a true diabetic cataract and is characterised by diffuse posterior and/or anterior, subscapular or cortical ‘snow-flake opacities [3]. Metabolic cataracts develop acutely with weeks or months with most of them needing surgery for improving visual acuity [4]. Very few case reports have described bilateral cataracts as a presenting feature of diabetes mellitus and as such are rarely seen in the present era owing to prompt diagnosis and early institution of effective surgery.

An 18-year-old female presented with progressive vision loss for the past 2 months. On enquiry, she also gave history of osmotic symptoms, weight loss and amenorrhea of 3 months duration. There was no history of trauma, recurrent stone formation and fractures, no history suggestive of adrenal insufficiency, thyroid dysfunction or family history of diabetes mellitus. Clinically, patient had low BMI (12.34 kg/m2), pallor and visible bilateral lenticular opacities with poor visual acuity (3/60 on Snellen’s chart). Rest of general physical and systemic examination was unremarkable (figure 1). Random blood glucose at the time of presentation was 519mg/dl, urine ketones were positive (3+) with normal ABG (pH=7.43,PCO2 38 mm Hg, HCO3 23), HbA1c was 9.8% . Patient also had iron deficiency anaemia [Hb: 6.7 g/dl, serum iron 10µg/dl (range:50-170), TIBC: 2340 µg/dl (range:250-450), ferritin: 4.56 ng/ml (range:18-160), serum IgA tTg: 1.65 U/ml (Normal < 15 U/ml), stool occult blood: negative]. Biochemical parameters including the calcium profile was normal and there was no evidence of any other endocrine dysfunction. [T3: 0.23 ng/ml (0.8-2.1), T4: 6.41 ug/dl (5.01-12.45), TSH: 1.43 uIU/ml (0.7-6.4), cortisol basal and post ACTH: 8.32 ug/dl/ 23.2 ug/dl, iPTH: 44 pg/ml, 25 OH vitamin D: 24 ng/dl]. She was initially managed with insulin infusion and intravenous fluids and subsequently shifted to basal bolus insulin. After achieving adequate glycemic control on basal bolus insulin patient was subjected to cataract surgery with intraocular lens implantation that led to normalization of visual acuity.

Figure 1. Bilateral cataract in a patient with type 1 diabetes mellitus.

The pathophysiology of cataracts in diabetes is not yet fully understood. High level of sorbitol has been demonstrated in the lens of animal models. In the lens glucose is converted to sorbitol by aldose reductase, which is subsequently converted to fructose by sorbitol dehydrogenase. The high levels of sorbitol increases the intracellular osmolarity and draws water into the lens altering its permeability and electrolyte composition, eventually leading to lens opacification [1]. Depletion of cofactor NADPH leading to an increase in oxidative stress maybe another probable mechanism [5].

This case highlights the fact that cataracts are a rare but a significant complication of type 1 diabetes. It is therefore prudent to screen for the potential diagnosis of new-onset type 1 diabetes mellitus in young patients who present with cataracts, as earlyrecognition of diabetes may prevent or ameliorate diabetic ketoacidosis or later complications of diabetes.