Gastroparesis: Given the easy fatigability and long-standing type 1 diabetes, gastroparesis is a common complication that can lead to delayed gastric emptying, affecting digestion and absorption of nutrients, thus impacting energy levels and blood glucose control.

Hypothyroidism: Common in long-standing type 1 diabetics due to autoimmune thyroiditis, which can cause fatigue, weight gain, and affect metabolic control.
Anemia: Could be due to various reasons including poor nutrition, chronic disease, or autoimmune hemolytic anemia, leading to easy fatigability.
Chronic Kidney Disease (CKD): A known complication of long-standing diabetes, which can lead to anemia, electrolyte imbalances, and fatigue.
Vitamin B12 Deficiency: Can occur due to metformin use (if added to regimen) or malabsorption, leading to fatigue, neuropathy, and anemia.

Addison's Disease: Though rare, autoimmune adrenalitis can occur in type 1 diabetics, leading to adrenal insufficiency, which can present with fatigue, hypotension, and hypoglycemia.
Celiac Disease: An autoimmune condition that can co-exist with type 1 diabetes, leading to malabsorption and potentially causing fatigue, weight loss, and poor glycemic control.
Sleep Apnea: Common in diabetics, can lead to significant daytime fatigue and impact glycemic control.

Pituitary Apoplexy or Hypopituitarism: Rare conditions that can affect hormone production, including adrenal and thyroid hormones, leading to fatigue, among other symptoms.
Mitochondrial Myopathies: Rare genetic disorders affecting muscle and mitochondrial function, which can cause fatigue, myopathy, and potentially impact glycemic control.
Diabetic Amyotrophy: A rare condition characterized by muscle wasting and weakness, typically affecting the proximal muscles, which can cause significant disability and fatigue.